Chapter 4 - The innovation

3rd Person POV

He is sitting hunched over the desk, the lens he used earlier earlier to see mana flow is resting on a small wooden base which looks like a coaster being punctured a hole, from that hole, through the lens, a string of gentle blue light came out, ascending. floating slowly around him are sigils, glyphs, some from this world, from foreign languages, and some that look like jagged shards of glass.

A knock on the door, and a voice came in "Arto, are you awake?" It's Rias' voice. She's cautious. She doesn't wait for an answer, but steps in. Arto turns to meet her gaze from his desk, "What seems to be bugging you at this hour, Rias? Sit down on the bed, I'll answer while working"

Rias obeyed, though she didn't lean back. She sat on the edge of the mattress, her posture rigid, watching the surreal display in the center of the room. The blue light emanating from the lens pulsed like a slow, rhythmic heartbeat, casting long, dancing shadows against the walls. The floating glyphs shifted and collided, merging into complex geometric patterns that seemed to fold into themselves, defying the three-dimensional space of the bedroom. To Rias, it looked like a star being born in a vacuum; to Arto, it was simply a rough draft of a translation.

"You're still working," Rias said, her voice barely above a whisper. She looked from the glowing sigils to the man, noticing the raw, red-rimmed state of his eyes and the way he gripped the edge of the desk. The air in the room felt heavy, charged with an intensity that made the fine hairs on her arms stand up. "I thought you would have collapsed from exhaustion by now."

Arto didn't look away from the floating shards of light. He reached out, his finger grazing a jagged glyph that looked like a lightning bolt frozen in obsidian. As he touched it, the symbol shimmered and dissolved into a sequence of fluid, cursive lines—the language of this world. "You're underestimating the work rate of a legion leader, princess, managing 10 million strongs isn't a job that you can complete by conventional 8 hours working period," he replied, his voice raspy and devoid of the polished charm he wore in the lounge.

"So shoot, what was troubling you? I know from your eyes that you came for something other than asking me some trivial questions like this" Rias remained silent for a heartbeat, her gaze drifting to the silver necklace draped around Arto's neck. She hadn't seen it before; he usually kept his chest covered, his presence a fortress of tailored fabric and disciplined posture. The pendant caught the blue light of the mana-lens, glinting with a quiet, melancholic luster.

The strategist in her wanted to ask about the translation—to secure the leverage she had just discussed with Akeno—but the woman in her saw a man who had just visited a grave in his mind. "I want to ask you something: What would you do if someone comes to you with a better deal than what I could offer?"

Arto stopped mid-motion. His finger remained poised an inch away from a shifting glyph, the blue light casting a sharp, skeletal shadow across his cheek. For a long moment, the only sound in the room was the rhythmic, low-frequency hum of the mana-lens. He didn't turn to look at her; instead, he let the glyphs collapse into a single, dense point of light before extinguishing them with a sharp flick of his wrist.

The sudden darkness made the silver pendant around his neck shimmer. He finally turned his chair, leaning back with a slow, deliberate movement. His eyes were tired, etched with a grief that hadn't quite faded, but his gaze remained as piercing as a winter morning.

"A 'better deal'," Arto repeated, his voice flat. He let the words hang in the air, weighing them as if they were physical objects. "You're not wrong, I might sway if a better price was set before my eyes, but that's also a test for your clan's commitment in the deal between us..."

He turns back to her, looking into her worried eyes "In our contract has a term about you securing my identity safe, that's my commitment to working to your clan, if you don't want me to know about another deal, you shouldn't let my identity and work known to others"

Rias felt a chill that had nothing to do with the room's temperature. The way he spoke was not aggressive, but it possessed the terrifying precision of a man who had already mapped out the exit strategies. He wasn't accusing her of a betrayal that had already happened; he was warning her about the one he suspected she was contemplating. He had seen the wheels turning in her head, the shifting gaze of a noblewoman calculating the value of a prize.

"I haven't told anyone, Arto," Rias said, her voice sounding smaller than she intended. She shifted on the bed, the silk of her pajamas rustling. "I was merely... thinking about the implications. The scale of what you're doing here. I don't want you to be a tool for the Gremory name, but I also know that once the world realizes what you can do, you won't be able to simply 'exist' anymore."

Arto let out a short, dry exhale that might have been a laugh in another life. He reached up, his hand rests on her head, rubbing gently "We signed a contract with each other, yes?" She nodded, Arto continues "Then you doubting means 2 things: you're not confident that you and your clan can keep me around, and there is a way to override the contract we signed from those with....better deals, right?"

Rias froze under the touch. His palm was warm, his gesture affectionate, yet his words were a surgical strike. The juxtaposition of the gentle physical contact and the cold, analytical interrogation left her feeling exposed, as if he were reading her thoughts like one of his magical primers. She wanted to protest, to tell him that her hesitation came from a place of care, but the logic of the mercenary was an airtight cage.

"It isn't about a lack of confidence in my clan, Arto," Rias replied, her voice regaining some of its strength. She leaned into his hand slightly, a reflexive need for the stability he provided. "It's about the world we live in. The Underworld doesn't reward modesty or secrecy; it rewards the bold and the powerful. I find myself caught between wanting to protect your peace and wanting to secure the future of my family. I suppose I'm realizing that those two desires might be in conflict."

Arto smiled, his hand doesn't leave her head "Then I've understood your goal, Rias, there is nothing conflicting between your 2 desires." He lifts his hand and looks at her in the eyes, the smile is still the same "You care about my emotions and well-being, that I deeply appreciate, not many cared about a living weapon like me. But...."

He leans closer to her "I said it to Akeno, and I will say it again, matter determines consciousness, every emotional bond should be placed on a solid physical foundation, and in this case, securing the future of your family and your growth using my knowledge. And when that foundation is strong, when your clan is at a higher position than now, when you're powerful enough to chase away threats that come our way, I get the wealth and security you agreed with me, by then, we can talk about emotions as a luxury rather than a necessity."

Rias felt a flicker of disbelief. She had spent the last hour agonizing over the morality of "using" him, only to find that Arto viewed the transaction as the very thing that made the emotional bond possible.

To him, the "gilded cage" she feared was actually the armor that protected the heart. He didn't want her to stop being a strategist; he wanted her to be a strategist for him.

"You make it sound so simple," Rias whispered, her tension finally bleeding out of her shoulders. "But the guilt... the idea of keeping you in the dark about your own worth... it felt like I was lying to you."

Arto's gaze softened, and out of nowhere, he pulls her into a hug, his arms wrapping around her with a strength that felt like an anchor in a storm. For a moment, the cold logic of the mercenary vanished, replaced by the warmth of a man who knew exactly how heavy a secret could feel. He let her lean against him, the silence of the room no longer charged with suspicion, but with a quiet, mutual understanding.

"Now that's what makes it hard to switch side, my dear Rias," Arto murmured, his voice vibrating against her temple. "You possess a conscience that most of the people I've known would have traded for a more efficient way to kill. It is a liability in a war room, but it is a luxury in a home. And that's exactly why I like being here, you truly care about me as a person, not just a tool."

He placed a kiss on the top of her head. "However, if you continue to brood over the ethics of our arrangement, you'll lose sleep. And a sleep-deprived Buchou is a grumpy Buchou, which is bad for the morale of the house."

Rias let out a genuine laugh, the sound finally breaking the oppressive tension that had saturated the room. She pulled back just enough to look at him, her expression a mixture of relief and admiration. "You always have an answer, don't you? You're infuriatingly composed, Arto."

"I know, now, do you like to join me in my journey of translating my magic into yours? If you're losing sleep, at least make it a productive one," Arto said, his voice returning to that calm, disciplined cadence. He shifted back toward the desk, gesturing for Rias to move closer.

Rias blinked, the sudden pivot from emotional intimacy back to academic rigor catching her off guard. She stepped toward the desk, her curiosity piqued. "You're actually letting me see the process? I thought you were keeping the core of your translation a secret until it was finished."

"You'll know it eventually, this Systematic Magic," He gestures at the floating glyphs around them "I will teach you and your peerage as a part of the training process we agreed, but the core architecture of the mana filter, I need to keep it to myself as my own way out, but you will get to use its function. For now, let us focus on the basics."

Arto reached out, his fingers captured 2 glyphs and placed each one over the flow of mana revealed by the lens, and from the other side of the glyph, the mana flows were bent in a certain angle and direction. "This is the core of magic, bent mana flows. A caster would send their stable mana flows into the spell circle, the glyphs will bend the mana flows into shapes to create the spell effect, that's what you call...Magic."

Rias leaned in, her eyes wide. As a high-class devil, she had always viewed magic as a fluid, intuitive process—a surge of power shaped by will and ancestral talent. Seeing it broken down into a series of geometric bends and redirections felt like seeing the clockwork behind a masterpiece. "You're treating the mana as a physical current. You're not just casting a spell; you're... engineering it."

"That's the nature of Systematic Magic, it views magic as a form of science, a science that uses other sciences to create what they never thought to relate to sciece, you use geometry to shape the mana flows, use math and physics to calculate the spell indexes, uses biology to cast plant-based and body debuff spells, use medicine to heal, use chemistry to cast poison spell, use psychology to cast mind control spell, and so many more" Arto explained, his fingers dancing through the air, shifting the blue glyphs with a precision that made Rias feel like she was watching a virtuoso pianist.

Rias watched as a small, circular glyph began to spin rapidly above the lens. "And how do you translate that into the languages of this world? The scripts we use are designed for intuitive flow, not for... calculations."

"That's where the translation comes in," Arto replied. He points towards the stable string of light from the lens "I will use the core function of magic as the base and the alphabet of glyphs in this book as a standard so that I can translate my alphabet into yours, if there is one similar, I can just use it, if it needs some changes, I'll change it, if it's different entirely, I will create a customized one....all for one goal, a standardize magical glyphs alphabet"

Rias watched, mesmerized, as he began to "stitch" the two systems together. He would isolate a specific frequency of mana and then cross-reference it with a devil's script, adjusting the curve of the glyph until the energy resonated perfectly. It was a painstaking process of trial and error, conducted with the patience of a man who had already spent centuries in silence. For the first time, Rias realized that Arto's strength wasn't just in his combat prowess or his mana reserves, but in this terrifying capacity for meticulous labor.

"Wait," Rias whispered, leaning closer. "If you standardize the alphabet, does that mean anyone can use these glyphs? Could a low-class devil suddenly cast a spell with the efficiency of a high-class one if they had the right formula?"

Arto paused, his gaze shifting to her. "In theory, yes. The barrier between classes in your world is largely based on the volume of mana and the innate 'feel' for the flow. But if you remove the 'feel' and replace it with a mathematical constant—a blueprint that works regardless of who is holding the pen—the gap shrinks. Power becomes a matter of knowledge rather than birthright."

"But that's the first step only," Arto continues speaking while his hand is working at a rate and precision even Rias finds hard to follow all his gestures "Because an alphabet without a proper grammar will change nothing. The end goal of this entire process is using the alphabet to integrate the main volume of Systematic Magic, the set of formulas that allows you to cast spells to your desire in....seconds instead of decades"

Rias felt a shiver of anticipation. To a devil, magic was an art of heritage—something refined over generations through bloodlines and rigorous, often intuitive, study. The idea of a "grammar" that could bypass the slow crawl of traditional mastery was revolutionary. She looked at the way Arto's fingers flicked, almost as if he were typing on an invisible keyboard, rearranging the laws of the universe into a legible script.

"Are you sure this can....work? Because something like this would fundamentally break the social order of the Underworld," Rias asked, her voice tinged with a mix of awe and a lingering sense of apprehension. She could almost see the faces of the Council members and the various Clan heads if they knew that a "blueprint" could replace the innate genius of a bloodline.

Arto smiles gently as he works, he could imagine Rias' curious eyes looking intensely at his work with fascination of a child seeing a magic trick. "The social order is a fragile thing, Rias. It is built on the assumption that the current way is the only way. But nature doesn't care about social order; it only cares about efficiency. If the 'old way' is too slow to survive a new threat, it will be replaced. That is not breaking the order; that is evolution."

He makes a final, sharp movement, as he re-draws a glyph with a slightly curvier detail other than the usual before placing it into the lens' light string, and the mana current bent in a way that seemed to ripple like a stone thrown into a pond. Nodding to his result, Arto places it into his notebook as another 'letter' in his 'alphabet'.

The work of his jagged hands is like a conductor leading an entire orchestra of light, Rias could sensed the fascination she felt when she saw magic for the first time, unconsciously, she leans into his shoulder to see his work clearly, mesmerizing all his actions and results. Arto noticed the closeness, the scent of her perfume mingling with the ozone of the mana-lens, and for a brief moment, the calculating mercenary's facade softened. He didn't pull away, allowing her to share in the quiet triumph of a successful translation.

"Can you...teach me how....." Rias' eyelids are getting heavier, even the light can't keep her awake, it's making her sleepiness stronger witnessing what could be called a magical dream before her eyes.

Arto noticed the way her breathing had slowed, her head now resting comfortably against his shoulder. The intense focus of the last hour had drained her, the mental exertion of trying to parse his logic while fighting off the late hour finally winning. He paused his movements, the blue light of the lens casting a soft, rhythmic glow over her sleeping features. For a man who had lived three thousand years in the cold calculations of war, this kind of vulnerability was still a foreign language, one he hadn't yet translated into a formula.

He didn't move to wake her. Instead, he shifted his weight, carefully adjusting his arm to provide a more stable support for her. He looked back at the notebook, at the newly minted 'letter' of his alphabet, and then back at the woman who was currently drooling slightly on his shoulder. The irony wasn't lost on him; he was building a bridge to a new era of power, yet the most significant thing in the room was the simple, quiet trust of a girl who had fallen asleep in the presence of a man who had spent centuries as a predator.

'I should move you to bed...but....' He thinks to himself, knowing letting her sleep like this would give her a morning with a sore neck '...I do need a company through this night....maybe being a little greedy isn't a sin for a mercenary.' He smiles before continuing his work, letting Rias' light breathing sound become the music that carries him through the night.

[Timeskip: Brought to you by chibi Rias sleeping on chibi Arto's shoulder]

Rias' eyes open slowly to the scratching sound of pen on paper, the view is still very blurry due to the light that she saw last night still glowing as she wakes up from a solid foundation of sleep. She feels the warmth of the sunlight streaming through the windows of the room, and for a moment, she forgets where she is.

Then she looks up to the vibration of the foundation she has been leaning on, she sees his face, Arto, still working digilantly while providing her a shoulder to sleep on. The scratching sound of the pen on the paper continues as Arto's hand moves with a precision that doesn't waver, his eyes focused on the shimmering remnants of the mana-lens' light. Rias blinks, the memories of the previous night rushing back—the conversation about value, the breathtaking display of Systematic Magic, and the sudden, overwhelming pull of sleep. She shifts slightly, realizing how deeply she had leaned into him, and a flush of warmth that has nothing to do with the sunlight creeps up her neck.

"Good morning, Princess," Arto says, his voice a low rumble that vibrates through her chest. He doesn't look at her, but his free hand reaches up to gently brush a stray lock of crimson hair from her forehead. "You slept for seven hours. Your breathing stabilized around three in the morning, but you seemed quite attached to my shoulder, so I decided it was an inefficient use of time to move you."

Rias lets out a soft, sleepy giggle, the sound feeling light and airy in the quiet room. She pulls back, stretching her limbs with a slow yawn, feeling more refreshed than she had in weeks. The guilt that had plagued her the evening before hadn't vanished, but it had transformed; it was no longer a jagged knot of anxiety, but a smooth, manageable understanding. She looks at the notebook on the desk, now filled with rows of alien symbols and translated scripts. The 'alphabet' was growing, a silent revolution written in ink and mana.

"Did you finish the translation?" Rias asks, her voice still thick with sleep but her eyes shining with curiosity. She leans in, glancing at the page. The complexity of the glyphs is staggering—they look less like letters and more like the blueprints for a star-engine.

Arto finally looks at her, a small, tired smile tugging at the corners of his mouth. "Far from it, there are still so much to do, I still need a few more days to complete it. But that's not the matter to care about now, how are you feeling? Is your neck hurt?"

Rias rotated her head slowly, testing the range of motion. To her surprise, there was no stiffness, only a lingering sense of warmth where she had been tucked against him. "Actually, no," she admitted, her voice regaining its melodic clarity. "I think I've had the most restful sleep of my life. Your shoulder is surprisingly ergonomic."

Arto let out a dry huff of amusement and finally set the pen down. He leaned back in his chair, the movement causing the silver pendant to clink softly against his chest. "Don't get used to it. My hourly rate for acting as a pillow is exorbitant."

Rias laughed, the sound filling the room and chasing away the last remnants of the previous night's heavy atmosphere. She looked at the notebook and then back at him, her expression softening. The man before her was a contradiction—a living weapon who spoke of systemic efficiency and strategic leverage, yet who had spent his night ensuring she didn't wake up with a kink in her neck.

"You're a strange man, Arto," she murmured, reaching out to lightly touch the sleeve of his shirt. "You talk about bonds as luxuries and emotions as secondary to foundations, but you're the most attentive person in this house."

"Because we're both delivering what the other requires, that's when our relationship receives a solid foundation, and we can talk emotions, but" He presses his fingers against the notebook "This is just the start of my delivery, and what you're feeling, the awe and amazement, they are just hope.....like an investor expecting the price of a stock to go up. So until the work is done, we need to stay a little more realistic, right?"

Rias smiled, though this time it was a more knowing expression. She knew he used the language of a contractor to shield himself from the vulnerability of being liked, but she had grown fond of the game. She stepped back, her gaze drifting to the notebook once more. The sheer scale of the task—standardizing an entire magical system—was daunting, but it also promised a future where she didn't have to worry about the fragility of her peerage's power.

"You're always calculating, Arto," Rias said, her voice regaining its playful confidence. "But it seems you've never understood women, they all have this thing called....Sixth Sense. And my sixth sense tells me that you actually enjoyed my company last night, and your work will be revolutionary. So until the day that your success comes, will you let me more than just your investor?"

Arto paused, his hand hovering over the notebook. He looked at her, really looked at her—the way the morning sun caught the crimson of her hair and the genuine, hopeful curiosity in her eyes. He had spent millennia viewing relationships as a series of exchanges, a sum of what one could provide and what the other could offer. But Rias wasn't just a strategic asset; she was a variable he couldn't quite solve.

"A la lune," he whispered, a phrase from a forgotten tongue that meant a gamble of the heart. He closed the notebook with a decisive snap. "Very well. If the investor wishes to diversify her portfolio into something as volatile as my company, I suppose it would be a breach of contract to refuse."

Rias beamed, the victory of the moment making her feel as though she had just won a high-stakes game of chess. She reached out, sliding her hand over his, her fingers brushing against the calloused skin of his knuckles. "I've always been a bit of a risk-taker, Arto."

[Timeskip: Brought to you by a phone ringing]

Rias is sitting at the living room of the clubhouse, Arto has already gone to sleep after an all-nighter, and the tea is brewing for a guest to arrive. Sona Sitri, the student council president, is standing in front of Rias with a confused expression. She has just read a report that the current stray hunt of Rias Gremory and her peerage, which resulted in the acquisition of a new member of her household.

"A warrior," Sona repeated, her eyes narrowing as she adjusted her glasses. "Who killed 6 mimic chests of Sirzechs-sama, and defeated 22 stray devils with a stray's sword and a broken arm, pulled you all in a chasing marathon for more than an hour in a state of 'extreme exhaustion' as you wrote in this report, and he outpaced you most of that time....and you reported that he is a...human? Rias, I know you are an imaginative person, but this is....absurd"

Rias didn't flinch, though she felt a flicker of amusement at Sona's skepticism. She leaned back in her velvet armchair, the steam from the brewing tea curling between them like a silent witness. "I understand how it looks on paper, Sona. The statistics are... unconventional. But the facts remain. He is a mercenary of an origin we don't fully comprehend, and his capabilities are far beyond the standard human baseline."

Sona set the report down on the coffee table with a sharp clack. "There is a difference between 'beyond the baseline' and 'physically impossible.' To outpace a high-class devil in a sustained sprint while injured is not a matter of training; it is a matter of biology.

If he is human, then he is a mutation that should be studied. If he isn't, then you have brought an unknown variable into the heart of the territory without a proper vetting process."

Rias's expression softened, her mind shifting toward the room upstairs where Arto was currently sleeping like a log. "He isn't a variable to be solved, Sona. He's a man who has lost everything and is looking for a place to exist without being hunted. I've seen his discipline, his loyalty, and his... peculiar way of looking at the world. He isn't a threat to us; he is an asset that provides a perspective we didn't even know we were missing."

Sona sighed, the tension in her shoulders dropping slightly, though her analytical gaze remained. "You've always been prone to following your instincts, Rias. But instincts can be blind spots. If this 'warrior' is as powerful as the report suggests, the other Great Houses will eventually catch wind of him. A weapon that can outrun a devil and outthink a strategist doesn't stay a secret for long. You're not just harboring a teammate; you're harboring a political lightning rod."

"Which is exactly why he is staying under my protection," Rias replied, her voice firming. "I am not asking for your approval of his presence, Sona. I am informing you that he is part of my household's operational structure. Whether he is a human, a ghost, or something else entirely is irrelevant. What matters is that he is my warrior."

Sona stared at her for a long moment, the silence stretching until the tea kettle began to whistle, punctuating the tension. A small, knowing smile tugged at the corner of Sona's lips. She didn't believe in "human" anomalies, but she believed in Rias's judgment—and more importantly, she believed in Rias's possessiveness.

"You're speaking with a level of conviction that usually only accompanies a new obsession. Very well. Keep your secret for now, but if this 'asset' causes a diplomatic incident, it will be your head on the chopping block, not mine."

Sona stood up, her posture returning to its usual rigid precision. "I'll omit the more... improbable details of the chase from the official archive, citing 'environmental interference.' But Rias, if he is truly as capable as you claim, I want to have a look as well. is he comfortable with going to Kuoh Academy as a student?

Rias paused, the image of Arto—a man who had led legions and weathered the Void—trying to fit into a high school blazer flashing through her mind. 'Is he too old for that, I wonder' Rias asked herself, thinking of the man's face, with the scars and war marks, he looks like a person in his 30s, or even older. But when they are covered by the spell of an illusion, they will look like a student.....barely

"I'll ask his opinion, if he wants to, I'll inform you for a clearance" Rias concluded, her voice carrying a hint of amusement.

Sona gave a stiff nod, her eyes lingering on the hallway one last time before she took her leave with her phone going to her ear. As the front door clicked shut, Rias let out a long, slow exhale, the silence of the clubhouse returning to its usual hum.

She looked toward the stairs, imagining Arto—a man who had likely seen empires rise and fall—trying to navigate the social hierarchy of a Japanese high school. The mental image of him sitting through a history lecture, probably correcting the teacher on the actual logistics of a medieval siege, made her smile.

She climbed the stairs, her footsteps soft on the carpeted landing. She pushed open the door to the guest room, finding Arto sprawled across the bed, still clad in his linens, his breathing deep and rhythmic. 

The morning light caught the jagged line of a scar on his forearm, a reminder that while he looked peaceful, he was a map of a thousand battlefields. He looked younger in his sleep, the hardness of his gaze replaced by a vulnerability that only appeared when he believed no one was watching.

Rias stepped closer, leaning over him. "Arto," she whispered, her voice a gentle ripple in the quiet. "Wake up, you lazy mercenary." Arto doesn't wake up, as expected, he turns aside, away from her call like a kid not waking up to his mother's call.

Rias chuckled and decided to be a bit more persuasive. She leaned down and placed a light, lingering kiss on his cheek, her crimson hair brushing against his jawline. Arto turns suddenly against the sensation, his arm swept at her, tackling the girl down the bed as he pins her down with his limps, his arm over her stomach while his legs over hers.

He is still sleeping soundly while holding Rias like a hugging pillow, his grip firm and instinctive, as if he were securing a precious cargo during a storm. His eyes are barely open, half-masked by the haze of a deep slumber, yet his body has reacted with the reflexive precision of a man who spent centuries waking up in enemy territory. Rias finds herself pinned beneath him, her heart hammering against her ribs—not from fear, but from the sudden, overwhelming heat of his chest against her side.

"You... you're a menace," Rias whispers, her voice breathless. She tries to squirm, but Arto's grip only tightens, his face burying itself into the crook of her neck. He lets out a low, guttural mumble, the kind of sound a bear makes when it refuses to leave its den in mid-winter.

"Five more minutes," Arto grumbles, his voice sounding like gravel being crushed by velvet. "The contract didn't specify waking calls via physical contact."

Rias laughs, the sound muffled against his shoulder. She manages to wedge her hand between them, poking his cheek with a playful finger. "Sona Sitri, an heiress of another house, just left the clubhouse. She's already suspicious of your 'human' status, and she's practically demanding a meeting. Also, we have a potential problem: the Student Council President wants to know if you're capable of pretending to be a high school student."

That phrase—high school student—acts like a bucket of ice water. Arto's eyes snap open, the clouded sleepiness vanishing in an instant to be replaced by a look of sheer, existential horror. "You know I've never been to school, right? How do you expect me to play a student?"

Rias's laughter bubbles up, a melodic sound that vibrates against his chest. She doesn't try to pull away from the embrace anymore, instead letting herself sink into the warmth. "You've led armies, Arto. You've navigated the Void and translated the fundamental laws of magic. Surely a few hours of trigonometry and literature aren't as daunting as a siege on a fortified citadel."

Arto remains frozen for a moment, the concept of 'homework' hitting him with more force than a high-tier spell. He slowly releases his grip, sliding off her with a fluid motion that speaks of ingrained combat reflexes, though his expression remains one of profound skepticism. 

He sits up, rubbing his face with a calloused hand, his gaze drifting toward the window. "The logistics are simple. I can mimic the dress, I can mimic the posture, and I can certainly mimic the level of boredom required to pass unnoticed. But the social architecture of a teenage hive? That is a battlefield for which I have no map."

"That's why you have me," Rias says, sitting up and adjusting her clothing, her eyes sparkling with mischief. "And Akeno. Between the two of us, we can coach you on the nuances of 'high school' behavior. I mean you're a natural charmer already with that spell and knightly demeanor of your's; you'll be the most popular boy in the entire school within a week."

Arto looks at her, his expression deadpan. "Does popular mean they will like me...or hate me? because the last time I was somewhat popular, people saw me as a monster who could dismantle a city block."

Rias lets out a light laugh, reaching over to pat his cheek. "In Kuoh Academy, 'popular' usually means the girls find you attractive and the boys find you intimidating. Given your... aesthetic, you'll fit right in. Just don't mention the part where you've lived through several eras of human history, and for the love of the Great Houses, don't try to 'optimize' the school's scheduling system."

Arto sighs, the sound heavy with the weight of a man who had fought gods but was now facing the horror of a home-room teacher. "Then have it your way, Rias, I do want to go to school to know how it feels like to be a student, a dream I never knew I had until this moment," he admits, a trace of genuine curiosity flickering in his eyes. "Now, will you leave me alone a little, princess, I need some sleep before I enter this new 'battlefield'?"

Rias doesn't leave. Instead, she leans in and plants another quick kiss on his forehead, a playful victory mark. "Not a chance. You're on the clock now, mercenary. Lunch is waiting, and Akeno is probably already preparing your 'orientation' wardrobe. Since you're so fond of efficiency, let's see how quickly you can transition from 'sleepy veteran' to 'honor student.'"

As Rias exits the room with a triumphant hum, Arto remains laying on his bed, little sleep is what he has been used to for centuries, but the sound of school makes the sleepiness go away with anticipation 'I wonder what it feels like....' Arto thinks to himself before rising from the bed for lunch, stretching his stiff back before going downstairs.

In the kitchen, the air is thick with the scent of grilled fish and miso soup. Akeno is humming a tune, her movements a choreographed dance of domestic efficiency. When Arto enters, her eyes light up, and she practically glides toward him, her expression carrying that familiar, playful glint. "Good morning, Arto-kun. I hope you're ready for your transformation," she says, her voice like honey. "Rias told me the news. A high school student! I've already taken the liberty of analyzing your measurements."

"Hey, who said you can measure him?" Rias steps into the kitchen with serious face "Your tendency will freak him out, Akeno." Akeno simply giggles, her eyes shimmering with a mischievous light. "Oh, Rias, don't be so possessive. This is a matter of sartorial precision. If Arto-kun's trousers are too tight in the thighs, he'll rip them the moment he takes a step—and while that would be a delight for some of us to witness, it's hardly appropriate for a first day of school."

"Even so, it's not your business measuring him, I'll do it myself" Rias declares, taking the tape measure into her hand with a proprietary flick of her wrist. She looks at Arto, who is currently leaning against the doorframe with an expression of profound resignation. 

He looks like a man preparing to walk into a firing squad, yet his eyes are tracing the way Rias's crimson hair catches the morning light, a small, hidden softness tempering his stoic gaze.

"No, no, Buchou, you're exploiting your position as the leader of this peerage to hog all of our newcomers to yourself, I know you were in bed with this morning, so it's only fair to let me take this task," Akeno countered, her voice a silky purr that masked a sharp competitive edge. 

She stepped closer to Arto, her presence a fragrant, enveloping warmth that rivaled the steam from the miso soup. "Besides, a man of Arto-kun's... proportions... requires a touch that knows exactly how to handle muscle density. Right, Arto?"

Arto shifted his weight, feeling like a prize horse being appraised by two very determined buyers. He looked from Rias's determined pout to Akeno's predatory smile and realized that the 'battlefield' of high school had already begun, and it was currently manifesting in the kitchen. "I have no opinion, you can fight all you want, I will take whoever measuring me for school uniform, now, I must have lunch before doing the dishes and get back to work," he said, his voice flatly pragmatic, though he couldn't help the slight amusement dancing in his eyes.

"Aha! He's avoiding the question," Akeno chirped, stepping forward with a grace that felt almost liquid. "Since he's so modest, perhaps we should just do it together. Efficiency, right? That's what Arto-kun values."

Rias paused, her eyes widening as she processed the suggestion. The idea of sharing the task was a strategic compromise she hadn't anticipated, but the thought of Akeno's hands lingering on Arto's chest while she measured his shoulders made her possessiveness flare. However, she glanced at Arto—who was already halfway to the dining table, completely indifferent to the brewing storm—and realized that if she didn't agree, Akeno would simply find a way to do it regardless. "Fine," Rias sighed, though she kept a firm grip on the tape measure. "But I lead the process. Akeno, you can assist with the... lower half."

Akeno's smile widened, a flash of triumph crossing her features. "Perfectly reasonable, Buchou."

The lunch that followed was a strange mix of domestic bliss and tactical planning. Between bites of grilled mackerel, Rias began outlining the 'Social Survival Guide for the Ancient Mercenary.'

She explained the concept of senpai and kouhai, the danger of the school's gossip mill, and the absolute necessity of pretending to be slightly less competent than he actually was. "If you solve every math problem in ten seconds and speak seven dead languages in history class, you won't be a student; you'll be a freak of nature," Rias cautioned. "The goal is 'distinguished but unassuming.' You are a transfer student from overseas. Be polite, be quiet, and let me handle the bureaucracy."

Arto lifts his arms up for Rias to measure his chest area "Satan, your chest is even bigger than mine" She giggles while holding the tape measure with her finger pinning on the number she just got from Arto's chest size, Arto's muscles were just too big for a high school student but then again he's a mercenary of thousand year and his body is a tool of war so it's naturally developed.

"Ahem," Akeno's voice is like a siren's call, she is already kneeling on the floor, her eyes traveling up Arto's legs with a hungry gaze. "Now for the lower half. Please stand still, Arto-kun. If you twitch, the hem might be... unfortunate."

Arto doesn't move a muscle, he just looks down at the two women surrounding him with a blank expression, "I know, don't worry, you won't feel even a budge....hey, stop touching my butt" She gave an exaggerated pout. "I can't help it~ Yours looks so delicious. In exchange, I'll let you touch mine if you want~"

Rias's face flushed a shade of crimson that nearly matched her hair. "Akeno! Focus on the measurements, not the... assets!" she scolded, though her own gaze lingered a second too long on the way the fabric of Arto's trousers strained against his thighs. 

"Girls, don't let this last until the end of the day, I still have works to do, have you finished measuring, or do I have to strip for you to have enough of your tendencies?"

The silence that followed was instantaneous. Rias froze, the tape measure still pressed against his ribs, while Akeno's hand paused mid-air, her fingers inches from his hip. Both women stared up at him, their expressions a mixture of shock and sudden, intense curiosity. 

Arto, for his part, remained entirely unfazed, his voice as flat and pragmatic as if he were discussing the inventory of a supply wagon.

Akeno was the first to recover, a slow, predatory smile spreading across her lips. "Oh, Arto-kun, you shouldn't make promises you aren't prepared to keep. I might actually hold you to that."

"Enough!" Rias exclaimed, though her voice lacked any real conviction. She hurriedly finished the measurement for his torso and stepped back, her face still burning. "We have the numbers. Akeno, please, let's just finalize the notes and let the poor man go back to his research."

Akeno let out a theatrical sigh, standing up and smoothing out her skirt. "As the lady commands, Buchou. But the tailor will definitely have a question about the thigh circumference. I'll just note it as 'exceptionally athletic.'."

As the 2 devils come to stand before him with all the measurement taken "Are we done, ladies? I need to get back to work." Rias shakes her head "We still have one last thing to consider before you can go, Arto, that is your name. Enrolling you into Kuoh Academy with the name Arto Abyssgard is quite....attracting, we should take a more....common Japanese name"

Arto blinked, his brow furrowing in genuine confusion. "What is....Japanese?" Rias stared at him, the silence in the kitchen becoming heavy. She looked at the man who could calculate the trajectory of a spell across a city block and rewrite the grammar of magic, yet seemed completely disconnected from the basic geography of the world he was currently standing in. 

"Arto...we are in a coutry called Japan and what related to this country like people, culture, and language...is called Japanese, you are communiating with us in Japanese, you know that?"

Arto paused, his expression remaining flat as he processed the correction. "Huh, I see, humu humu, so I am talking in Japanese, I get it now, but still don't know why how I could understand what you're saying without any learning, I was here like....2 days ago"

Rias stared at him, her mouth slightly agape. "Arto, you've been speaking and understanding Japanese since the moment you stepped into this clubhouse. How can you not know what the language is called?"

Arto shrugged "Hey, I am from another world, we have a different world map, different names for things, different languages, and I haven't opened the geography book to read because I was too busy with translating magic for you, my dear investor, thank you"

Rias stared at him, the absurdity of the situation finally overriding her frustration. Here was a man who could dismantle the logic of a high-tier spell in seconds, yet he had simply assumed he was speaking a nameless tongue because he hadn't bothered to check the local map. He was a master of the "how" and the "why," but the "where" was an irrelevant variable in his quest for stability.

"You are the most infuriatingly brilliant man I have ever met," Rias sighed, leaning her forehead against his chest for a brief moment. She pulled back, her eyes shimmering with a mixture of affection and amusement. 

"As for the name, 'Arto Abyssgard' sounds like a final boss from a dark fantasy novel. If you walk into a classroom with that name, you won't be 'distinguished but unassuming.' You'll be the center of a storm. We need something that blends in. Something....that represents your traits"

Akeno raises her hand, an idea came to her "How about 'Arata Akihiko', Buchou? Arata (新) means 'fresh' to represent his new life in a new world, Akihiko (明彦) means a 'bright prince' like that facade that caused the women in the mall to swoon over him when he appeared for the first time. It's common enough to not be weird, but unique enough to fit his... presence."

Arto tilted his head, testing the sounds. "Arata Akihiko. I like it...no, I gocmin love it. It sounds far less like a warning sign and more like someone who knows how to blend into a crowd." He looked at Rias, a rare, genuine glimmer of amusement in his eyes. "Though I suspect the 'prince' part is a variable Akeno added for her own amusement."

"Spot on, Arto-kun~" Akeno chirped, leaning in to give his arm a playful squeeze. "A bit of charisma is a necessary tool for any student. Now, about that 'stripping' comment from earlier—I think we should revisit that as part of your cultural orientation. After all, a mercenary needs to be comfortable in all environments."

Rias groaned, stepping between them and pushing Akeno back with a huff. "No more 'orientations' for today! We have a name, we have the measurements, and now we have a plan." 

She turned back to Arto, her expression softening. "Arata Akihiko. From this moment on, until the day you decide to leave this academy, that is who you are to the world. Do you think you can handle the transition, Arata?"

Arto let out a slow, rhythmic exhale, his posture shifting. The relaxed, sleepy man vanished, replaced by the focused warrior who could read the wind for a coming storm. He didn't just stand; he occupied the space, his presence expanding until he seemed to dwarf the kitchen. "As long as the 'bright prince' is allowed to maintain his independence, I can play the part,"

[Timeskip: Brought to you by chibi Akeno handing Arto's measurement to the schoolboard, making them shock because of his size]

Arto is standing his room, before the finished alphabet of magic glyphs he finished translating after 3 days of working endlessly, his eyes are darkened even more than his usual state due to lack of sleep that both Rias and Akeno can't convince him to do otherwise

'This 'coffee' thing....' Arto looks at an arry of cups he has drunk, the fragrance of the dark water fills the room as he can feel himself staggering backward, '...is so similar to Konfis...only more bitter....' He think of the drink he used to consume to stay awake back in his world, still grounded roasted beans that tasted like dirt but kept the mind sharp.

He looked at the final glyph he had just carved into the slate—the final piece of the new alphabet of magic, the standardized framework where his old but new magic will stand on to empower the family he is serving. 

The symbol shimmered with a faint, iridescent light, humming with the resonance of a mathematical absolute. He had done it. He had bridged the gap between his forgotten history and the current reality, creating a system that didn't rely on bloodlines or divine favors, but on the sheer, cold logic of existence.

The door to his room creaked open. Rias stepped in, her expression shifting from curiosity to immediate alarm as she spotted the graveyard of coffee cups littering his desk. "Arto! I told you to sleep at least four hours! You look like you've been fighting a war against your own eyelids."

Arto blinked, his eyes bloodshot but shimmering with an intensity that made Rias pause. He didn't look tired; he looked electrified, as if the sheer volume of data he had processed had rewritten his internal circuitry. 

He pointed a trembling finger toward the notebook. "It's gocmin done, Rias, I've finished mapping my own glyphs alphabet into this world's magic system, what's left is the formulas, and I will start right...."

Before he could finish the sentence, Rias comes to him, stomping so hard the entire clubhouse seems trembling as she holds Arto by his shoulders and with her monstrous strength, she throws him onto his bed. 

The impact is loud, a heavy thud that echoes through the room, but Arto is too exhausted to fight it. He simply stares at the ceiling, his mind still racing with geometric constants and mana-flow vectors, while the world around him begins to blur into a hazy, coffee-stained smear.

"The formulas can wait until you can see straight!" Rias commands, her voice firm but laced with a deep, simmering worry. She doesn't let him move, climbing onto the bed and practically pinning him down with her own weight, her hands pressing against his chest to keep him from sliding back toward his notebooks. "You're obsessing again. I can see it in your eyes—you're trying to solve the world like a puzzle, but you're forgetting that you are a living being, not a mathematical equation."

Arto can't fight it anymore as he finally closes his eyes and sleep like immediately. His mind, which had been a storm of calculations and geometric constants, finally goes silent, drowned out by the rhythmic thumping of Rias's heart against his chest. 

The smell of old ink and roasted beans clings to him, but the warmth of the crimson-haired devil acts as a natural sedative, pulling him down into a dreamless, heavy void.

Rias remains still for a long time, her cheek resting against his collarbone. She listens to the slow, steady cadence of his breathing, feeling the tension bleed out of his muscular frame. He is so terrifyingly powerful, yet in this state, he looks like a man who has finally found a place where he doesn't have to be the one on guard. 

She reaches out, her fingers tracing the line of his jaw, brushing away a stray smudge of graphite. "You really are a fool," she whispers, her voice softening into something profoundly tender. "Solving the secrets of magic, but unable to remember to eat a proper meal."

The peace is shattered about three hours later by the sound of Akeno's voice echoing from the hallway, sounding far too cheerful for the current state of the room. "Buchou~ I've just returned from the tailor! The 'Bright Prince's' attire is ready for a final fitting!"

Rias bolts upright, nearly knocking Arto off the bed in her haste to disentangle herself. She scrambles to her feet, her face flushing a bright pink as she realizes she had been practically cuddling the unconscious mercenary. "Akeno! Don't just barge in!" she hisses, though she is already moving toward the door to intercept the other woman.

Akeno, however, is faster. She glides into the room, holding a garment bag with a triumphant smirk. Her eyes immediately fall on Arto, who is beginning to stir, his eyelids fluttering as he returns to the waking world. "Oh my, did I interrupt a private session? I'll have to inform Lord and Lady Gremory about how their daughter found her haven in a man from another world," she teases, her voice a playful purr.

"Don't let me place a mind wiping spell on you, Akeno, I was just....." Rias paused, her voice trailing off as she realized the position she had been in. She cleared her throat, stepping back and smoothing her dress with a sudden, frantic need for composure. "I was just ensuring he didn't roll off the bed in his sleep! He's an unstable sleeper!"

"And how did you know about that, Buchou~?" Akeno teases further. "Did you sleep with him to know? Rias's face transitioned from a soft pink to a vivid, alarming crimson. "I did not—we were not—it was a tactical positioning for the sake of his health!" she sputtered, her voice rising an octave. "He has been awake for 3 days and he needed sleep, so I have to force his hand!"

She turns back to the sleeping form of Arto before coming towards Akeno to push her out of the room "Let's go he needs some space and time to rest properly, we can do the fitting later! Out! Out! Now!" 

Akeno was about to protest, but seeing her King's face is funny enough, more would make her explode from laughter, so she gracefully retreats from the room, humming a playful tune as she closes the door.

[Timeskip: Brought to you by chibi Akeno teasing chibi RIas]

The moment Arto wakes up, the silence of the room feels heavier than usual. He doesn't remember the exact moment he fell asleep, only the sensation of Rias's weight and the rhythmic drumming of a heart that beat with a terrifyingly honest sincerity. 

He sits up slowly, his muscles stiff, and looks at the notebook of glyphs resting on his desk. The iridescent glow has faded into a steady, dormant hum, a silent testament to a bridge he had finally built between two worlds.

He rises and moves toward the mirror, catching a glimpse of the man staring back. He looks older than his face suggests. But as he thinks of the name 'Arata Akihiko,' a small, ghost of a smile touches his lips. A bright prince. The irony is almost poetic; he was a weapon forged in the abyss, now being dressed in the cloth of a scholar.

A sharp knock at the door precedes Rias's entrance. She isn't shouting now; her voice is soft, almost cautious. "Arto? Are you awake? Akeno is waiting with the uniform, and we have a schedule to keep if you're going to survive your first day without looking like a vagabond."

He opens the door to find her holding a tray of tea and a small plate of fruit. She doesn't look at him directly at first, her cheeks still holding a faint, lingering warmth from their previous encounter. 

"You don't remember what happened yesterday, right?" She asks with her cheek burning, seemingly expecting him to not remember how she threw him on the bed with her strength and pinned down with her body so that he could sleep.

"I...don't, princess, the only thing I remember was falling down my bed after completing my glyphs translation," Arto replies, his voice still raspy from the coffee-induced dehydration. He takes the tray from her, the scent of fresh tea grounding him in the present. 

He looks at her and notices the way she avoids his gaze, the slight tremor in her hand. "So, what do you want to talk about, Rias? I am sure you're here for more than just a tray of tea" 

He pours the tea for her before handing her the cup before using the fork to pick up a piece of apple for the princess. "Sit down, let us talk, I think it's about me and my innovations"

Rias took the apple slice with a small, appreciative hum, though she didn't sit immediately. She lingered by the edge of the desk, her eyes drifting toward the notebook of translated glyphs. 

The sight of those shimmering symbols—the bridge Arto had built between his lost world and this one—made her heart swell with a mixture of pride and apprehension. "You're right," she admitted, her voice regaining its steady, authoritative tone. "The innovations. I want to ask you to do something for me, Arto."

Arto leaned back in his chair, the tea steam curling around his face. "What is it?" Rias comes into the room, taking the chair Arto has been sitting the past few days while looking a the man who is sitting on his bed "I want to see the mana 'filter' that you built, the one that allowed you to conjure up enough mana to manifest a car, the thing that can filter wild mana into stable, ambient flow for magic casting. Also, are you comfortable with showing it to my parents as well?"

Arto's expression didn't change, but his eyes narrowed slightly. The "filter" was essentially a conceptual lung—a way to breathe in the chaotic energy of the world and exhale it as a refined, usable fuel. 

It's a almost unlimited source of green energy working in an endless recycling circle. and it was his primary bargaining chip to put on the table for the supports of Gremory clan "Apparently, I can do that, but under some conditions"

Rias leaned forward, her curiosity piqued. She knew Arto didn't negotiate out of greed, but out of a fundamental need for security. "Name them," she said softly. "Whatever you need to feel secure in this arrangement, just tell me."

"First," Arto began, counting on his fingers, "the filter is a piece of my personal methodology. If I show it to your parents, it must be under the agreement that the core architecture remains with me. I will provide the results—the energy output and the stability—but the how remains my intellectual property. It's the only way to protect myself in case you or your clan turn against me."

Rias didn't hesitate; she knew how the world of nobility worked, and she knew that for a man like Arto, autonomy was more precious than gold. "Agreed. My father values talent, but he respects a contract even more. I'll ensure the agreement is formalized."

"Second," Arto continued, his gaze shifting to the window where the late afternoon sun was casting long, amber shadows across the room. "All the manufacturing process of copies of this mana filtering glyph will be under my control, one switch of mine and all the glyphs will go out, I want my say in their usage."

Rias felt a flicker of surprise at the boldness of the request—essentially asking for a kill-switch on the technology he was gifting the Gremory clan—but she quickly suppressed the instinct to argue. To anyone else, this would be an act of hubris or a threat. 

To Arto, it was simply a safety mechanism, a way to ensure he wasn't discarded once the "machine" was built. "A bold request," she whispered, a small, proud smile playing on her lips. "But further negotiation is still needed and my parents will take care of that. Are there anything else?"

"One last thing," Arto said, his voice softening as he looked at her. "I want the highest commitment of Gremory in protecting my identity, because you know what comes with this filter, right? It's magic-tech, imagine machines run on mana that could work almost forever, factories without smoke, cities that don't need fuel... it's a catalyst for war. If the Underworld's other clans find out, I become a target for kidnapping or worse. I don't want to be a prize in a political game."

Rias reached out, her fingers brushing against the back of his hand. The warmth of her touch was a stark contrast to the cold, clinical nature of the negotiation they were conducting. "You have my word, Arto. Not just as the heir of the Gremory clan, but as your friend. I will personally oversee the security of your cover. You aren't a tool to be used; you're a part of my life now."

The tension in Arto's shoulders finally dissipated. He didn't believe in promises—thousands of years of war had taught him that words were cheap—but he believed in Rias. 

She was the first person in an eternity to treat his autonomy as a priority rather than a nuisance. "Fine. We have a deal. Now, let's go meet your parents before Akeno decides to dress me in something that requires a cape."

Rias laughed, a bright, genuine sound that filled the room. "Trust me, the cape is probably the least of your worries. Akeno has a very... creative vision for your 'Prince' persona." She stood up and offered him her hand. 

Her expression shifting from the protective friend to the focused leader of a peerage. "The meeting with my parents will be handled via a secure magic circle. They are eager to see the man who has captured my interest so thoroughly, both strategically and... otherwise."

Arto took her hand, allowing her to pull him toward the door. As they exited the room, they found Akeno waiting in the hallway, leaning against the wall with the garment bag draped over her arm like a trophy. "Ah, the sleeping beauty awakens! And just in time. The tailor has finished the final adjustments, but since the 'Prince' is so uniquely proportioned, I think it's only fair that I help him into the uniform personally."

"You can do that later however you want, Akeno, we are have a meeting with my parents to talk about the further cooperation between Arto and our clan," Rias interjected, though she didn't let go of Arto's hand and pulled him past Akeno to her own room, where the summoning circle for the Gremory family was prepared.

Arto followed with a tired sigh, glancing back at Akeno, who merely winked at him. Stopping before the door of the room, Rias stopped and turned to Arto "Please wait out here a little, Arto, I need to speak to them first, then I'll let you in when it's right, okay? I can't let you see the process of accessing the secured line"

He nodded, leaning his back against the wall and sliding down until he sat on the floor, his long legs stretching out across the hallway. The silence of the corridor was punctuated only by the distant, muffled sounds of the clubhouse.

Inside the room, the air shimmered. Rias stood before a complex array of crimson runes that pulsed like a living heart. As she activated the circle, the space within the glyphs distorted, revealing a lavishly appointed study in the Underworld. Two figures dominated the scene: a man with a commanding presence and a woman whose kind eyes mirrored Rias's own, though her expression was one of profound intrigue.

"Father, Mother," Rias began, her voice steady but brimming with excitement. "A few days ago, in the trap we set for the group of stray devil we have been pursuing, we encountered and recruited a person of... extraordinary capabilities. He is not from our world, nor is he a servant by contract, but he has agreed to a partnership based on mutual benefit."

Lord Gremory leaned forward, his gaze narrowing. He was a man who could read the atmospheric pressure of a room, and Rias was practically radiating a sense of protective pride. "A partner, Rias? You usually prefer the certainty of a piece," he noted, his voice a resonant baritone.

"He is a mercenary from another world, Father. A warrior who possesses a logical approach to magic that defies our current understanding. More importantly," Rias paused, leaning into the crimson light of the circle, "he has developed a mana filtration system. A method to stabilize ambient energy into a perpetual, refined flow. He calls it a 'filter.' If integrated into our territory, it could revolutionize the way we sustain our wards and our economy."

The shift in Lord Gremory's expression was instantaneous. The curiosity vanished, replaced by the sharp, calculating intensity of a high-ranking noble. "A perpetual filter? Such a thing is theoretically impossible. The laws of thermodynamics and mana-saturation usually prevent a closed-loop system from remaining stable."

"That is why he is a genius, Father," Rias replied with a smirk. "May I bring him in?" Lady Venelana was the one more eager than most, her eyes shimmering with a scholarly hunger. "Please, Rias. A man who can rewrite the fundamental laws of energy is a rarity in any world."

Rias stepped back from the circle and opened the door. Arto didn't walk in so much as he drifted, his presence filling the room with a sudden, heavy stillness that made the air feel thick. 

He bows respectfully before the leaders of the clan he is giving his service to "Lord and Lady Gremory, it's a pleasure to finally meet you in person. My name is Arto Abyssgard, the new addition to your daughter's roster."

Lord Gremory's eyes narrowed, scanning the man. Arto looks like a mercenary like As described with scars, sunkened eyes and predatory eyes, but his posture and demeanor screams aristocratic origin, it's the duality of a man who has've seen the lowest pits of hell and the highest peaks of power.

"The pleasure is ours, Arto Abyssgard," Lord Gremory replied, his voice echoing with a power that would make a lesser man tremble, though Arto didn't even blink. "My daughter speaks of you as if you are a miracle wrapped in a tragedy. She tells me you have solved a problem that has plagued the magical sciences for millennia. The 'Filter'—do not tell me the theory. Show me the result."

Arto didn't need further invitation. He stepped toward the center of the room, but to their surprise, he raised his hand and darkness bloomed around the study—opaque, velvet-black veil that swallowed light and sound alike, sealing the entire space in perfect isolation. Even the communication circle's glow dimmed slightly, as though muffled.

Rias startled. "You don't need to be that secretive, Arto—" His face was no longer the gentle, slightly bemused knight she knew. It was hard, serious—eyes scanning corners that shouldn't need scanning. "Someone was definitely watching us right now," he said quietly. "I felt the probe the moment the moment I stepped into the room. Subtle, but there."

Lord Gremory's eyebrows shot up, his gaze shifting from the man to the void-shrouded walls of the room. The air in the study grew heavy as the high-tier devil instinctively shifted into a combat stance, his aura flaring in response to the perceived breach of his privacy. "A probe? In the heart of the Gremory territory?"

"Yes, the line is tightly secured, but the room is not, and as long as the watcher could see what you're talking in here, no matter how tight the secured line is, the secrets will always spill," Arto replied calmly, his voice cutting through the tension like a blade. 

He didn't look at the communication circle; his eyes were fixed on the ceiling, tracking the invisible ripple of a surveillance spell that had tried to eavedrop them "It's gone, either they have gotten what they want, or they have failed, we don't know for sure. Now, about the filter, which I will call from now on, Stabilizer"

He lifted his hand. Between his fingers materialized a small, glowing sigil—compact, intricate, and utterly alien to devil eyes. The lines were neither the flowing curves of demonic magic nor the rigid geometry of fallen angel script.

They twisted in ways that seemed to defy perspective, yet felt perfectly balanced. "This," he said quietly, "is the core of what I was talking about. The solution to the persistent problem both our worlds have had with mana."

He stepped closer to the circle's edge so the Gremory lords could see clearly. "I call it the Stabilizer. And ironically, its nature lies in something every living being that can absorb mana already does unconsciously."

Rias, Zeoticus, and Venelana nodded—everyone knew the basic truth. Arto continued, voice calm but carrying the weight of certainty. "We absorb chaotic ambient mana from the environment and convert it into stable internal reserves. That's how we recover mana naturally. But raw environmental mana is too turbulent for direct spellcasting. So how do our bodies tame it?"

Zeoticus's eyes narrowed in realization. "You're referring to the natural biological filter every mana-sensitive organism possesses—the process that refines wild flows into usable ones."

Venelana finished the thought, voice soft with dawning understanding. "That process is extraordinarily complex. No one has ever fully mapped it, let alone replicated it artificially. And you're telling us…" Rias completed it, staring at the sigil with open awe. "…you've fully understood, optimized, and compressed it into a single sigil capable of processing wild mana at industrial rates."

Within the sealed darkness of the veil, Arto exhaled once—steadying—and let the sigil flare brighter. The Stabilizer rotated slowly in his palm, its alien lines beginning to pulse with faint, controlled light. "The proof," he said simply, "begins now."

With a subtle twist of his wrist, the small sigil expanded—unfolding like a blooming flower of pure mana. Lines stretched, interconnected, and layered until a perfect, intricate mandala nearly two meters across hovered in the air before him. It glowed with a soft, steady azure light—neither demonic red nor holy gold, but something neutral, almost crystalline.

"This is the full version of the Stabilizer," Arto explained, voice calm but carrying the weight of revelation. "A spell designed to tame wild mana. Normally, any spell consumes mana to maintain itself. But the ratio here has been optimized to one in one hundred billion. For every hundred billion units of chaotic ambient mana it processes… only one is needed to sustain the field."

Lord Gremory leaned in, his eyes wide as he watched the azure mandala pulse. He could feel it—the air around the sigil was becoming unnervingly pure, stripped of the jagged static that usually accompanied high-density mana. 

It wasn't just absorbing energy; it was purifying the very atmosphere of the room. "You've created a self-sustaining engine of refinement," Zeoticus whispered, his voice trembling with a rare mixture of shock and greed. "The efficiency is... it's practically divine."

Rias's eyes widened. She could feel it: the chaotic eddies that always tugged at her power were gone. The mana around her flowed like calm water, ready to be shaped. 

Zeoticus and Venelana leaned forward on the other end of the circle, expressions shifting from cautious interest to open astonishment. "You can actually cast spells in here without using your own reserves," Arto said, turning to Rias. "Try it."

Rias hesitated only a heartbeat. She raised her hand—no incantation, no draw from her personal well—and simply willed a small sphere of crimson Power of Destruction into existence. Normally, even a basic orb would require a flicker of her own mana to form and maintain. This time… nothing.

The sphere materialized instantly, hovering above her palm, perfectly stable and drawing sustenance solely from the tamed ambient flow. It glowed brighter than usual—cleaner, more potent. Rias's breath caught. She let it grow—larger, denser—until it was the size of a basketball, spinning slowly with contained annihilation. Still no drain on her reserves.

On the other side of the circle, Venelana's teacup clattered softly against its saucer. Zeoticus's voice was hushed. "…Impossible." Arto allowed himself a small, satisfied nod. "This is only the beginning. With proper physical laws confirmed, I can refine it further—scale it, shape it, integrate it into machinery. Endless power. Clean. Stable. Unlimited."

The silence that followed was absolute. Lord Gremory didn't speak for a long time, his eyes locked on the azure mandala as if expecting it to vanish. When he finally spoke, his voice was no longer that of a curious noble, but of a strategist who had just seen the board be flipped over entirely. "The geopolitical implications of this are staggering," Zeoticus murmured. 

"If other houses knew that a single man could provide a source of power that renders traditional mana crystal mining obsolete, they wouldn't just want to partner with you, Arto. They would try to dismantle you to find the secret."

Arto's expression remained neutral, though his eyes flickered toward the edge of the room where his void-veil still held the perimeter. "Which is why keeping my identity and works is important, your clan is a political force strong enough to wave off the prying eyes and spread the achievement on a scale large enough for enemies to never be able to pinpoint the true author behind all the innovations"

Arto closed the Stabilizer into a single sigil with a snap, signalling the spectacle has overstay its welcome "Now, you've seen the new era before your eyes, it's time for the conditions to get to it. I've said this to Rias, and I will lay my terms out again" He raised one finger "The idetity must remain hidden on the highest level,"

Another finger is raised "I will keep the key to the core architecture of Stabilizer to myself, you will use its functions for your goals, but I must have my say in those goals so that you won't be able to betray me mid-way and use my innovations for goals that is breach my standards" He said confidently like he is owning this entire negotiation.

The third finger is raised "I will have a cut in every piece of advancement using Stabilizer, but it will come with future advancements when I bring my own magic-tech into the play, right now, I am comfortable with books to learn, a roof to stay under, good foods, and great companies in your daughter and her peerage."

Lady Gremory stared at the man. Most who stood before her and her husband were either trembling in fear or bowing in submission; Arto did neither. He stood with the poise of a man who understands too well his own values and how revolutionary it is to whoever invests in him, that intellectual arrogant of a politician who knows he is winning the room.

"You are a fascinating man, Arto Abyssgard," Zeoticus Gremory said, a slow, genuine smile spreading across his face. The greed from earlier had settled into a profound respect. "Most would have tried to sell this as a one-time miracle for a mountain of gold. You, however, are negotiating for a seat at the table and a leash on the technology. You don't want wealth; you want leverage."

"Leverage is the only currency that doesn't deflate, Lord Gremory," Arto replied, his voice neutral. "Agreed," Zeoticus stated firmly. "The Gremory clan will protect your identity with the same fervor we protect our own blood. We will provide the resources, the security, and the 'cover' Rias has proposed. In exchange, the Stabilizer becomes the cornerstone of our house's future, with the understanding that the architect holds the keys."

He paused, glancing at Rias with a look of immense pride. "It seems our daughter has a keen eye for talent. You have not only found a warrior, Rias, but a paradigm shift." Lady Gremory next to him smile gently, but Arto can still see the edge behind that smile, like she was not satisfied with this settlement, but still has to accept the current situation, where a human gained the upperhand against them.

"A fine play, my boy" the woman spoke finally, her voice is like dripping honey laced with dangerous edges. Venelana Gremory's smile didn't reach her eyes, which were still calculating the exact trajectory of the power shift Arto had just introduced. "Leverage is indeed a currency, but be careful not to hoard too much, or you might find yourself the only target in a room full of hungry predators."

Arto didn't flinch. He can feel her getting annoyed not having a say in this negotiation, both from her husband's eagerness to strike a deal, and from a fact that what Arto wields couldn't be left dropping into another's hand....no matter the cost.

"Then I've already gotten you as my protector, yes? Unless you don't have the confident to keep me safe from other houses, Lady Gremory," Arto replied, his voice devoid of malice but laced with a playful challenge. He wasn't just testing her; he was establishing that while he respected the hierarchy, he would not be intimidated by it.

Venelana's eyes flashed—not with anger, but with an appreciative spark of amusement. She let out a soft, melodic laugh that echoed through the void-shrouded room. "Confidence is one thing; arrogance is another. But in your case, the arrogance is backed by a result. I find that... refreshing, I'll personally draft the deal between us, Arto. I enjoy the details more than my husband does."

Zeoticus let out a huff of amusement, waving his hand to signal the end of the formal session. "Enough posturing for one day. You have a deal, Arto. Rias, ensure he is well-integrated into the household. If he is to be the architect of our future, he cannot be living out of a suitcase." With a final, lingering look of profound curiosity and calculation, the image of the Gremory lords flickered and vanished, the crimson runes fading into the floor.

The oppressive weight of the high-noble aura vanished instantly, leaving the room feeling suddenly spacious and quiet. Arto exhaled a long, slow breath, the tension finally leaving his frame as he stepped out of his 'negotiator' persona. He leaned back against the wall, his eyes closing for a moment.

"You really like to play with fire, don't you?" Rias asked, her voice brimming with a mix of anxiety and admiration. She walked toward him, her footsteps light on the carpet. "Challenging my mother to her face? Most devils would have spent an hour rehearsing their greeting just to avoid a frown."

Arto opened one eye, a ghost of a smirk playing on his lips. "She was testing the structural integrity of my resolve, Rias. If I had blinked, she would have known exactly where my breaking point was. In a room full of predators, the only way to stay safe is to convince them you're the one with the teeth, a good lesson to learn as a politician and leader, letting them know you are not to be bullied."

[Elsewhere]

In a sleek, modern apartment overlooking Kuoh's quiet nighttime streets, Sona Sitri stood by the window, phone pressed to her ear. The city lights reflected in her pink oval glasses, but her expression was anything but relaxed.b"I see. Thank you, Spy," she said coolly. "But remember our deal."

On the other end, a voice like honeyed silk replied. "It's a pleasure working with you, Miss Sona. As for our deal—the intel will not be on the display shelf. I've received the payment. You're welcome."

A soft laugh. "And about your offer to me… I must decline." The line went dead. Sona lowered the phone, exhaling slowly. "That woman," she muttered. "Always knows before I even open my mouth."

She turned from the window, gaze sharpening. "But it's all right. I'll come back with another deal." Her eyes drifted to the distant silhouette of the old school building—the Occult Research Club clubhouse. "So this is what you've been hiding from me, Rias."

Her voice was quiet, but carried the weight of someone who disliked surprises—especially from supposed allies. "We rule this town together. That means intel must be transparent between us. But with this…" She adjusted her glasses. "I know you're protecting his knowledge. And you'll stop any attempt I make to recruit him for my peerage."

A pause. Sona's lips pressed into a thin line. She dialed again—this time a secure line. "Mother. Father," she said the moment the connection opened. "Something urgent has come up. We need to have a talk with the Gremory clan about… a classified asset."

On the other end, her parents' voices overlapped briefly—curious, concerned, attentive. Sona's gaze remained fixed on the distant clubhouse lights. "One that could change everything," she added softly.

[Arto's study]

Arto closed the door behind him with a soft click, the sound echoing slightly in the quiet room. The lamp on his desk still burned low, casting warm light over the scattered notes, the open primer, and the faint afterglow of the sigils he'd been testing earlier.

He took two steps toward the desk—then stopped. The air felt… off. Not hostile, but watched.

His gaze flicked to the notebook he'd left open: the page with his latest sigil sketches, equations, and the Stabilizer's core formula. A tiny ripple shimmered just above the paper—barely perceptible, like heat haze over asphalt.

Arto sighed, long and tired. "It's encrypted my way," he said aloud, voice calm but carrying a clear edge. "Don't try to read it."

He reached out with casual speed, fingers closing around something invisible. A faint shimmer of silver light revealed what he had caught: a disembodied, translucent eye, no larger than a marble, floating mid-air. Beside it, almost completely hidden until now, hovered a delicate, shell-like ear.

Both constructs pulsed once, weakly, as if startled to be discovered. Arto held the eye up to his own face, studying it without anger—just quiet recognition. "We'll meet again… soon."

His voice was low, almost gentle, but the promise in it was unmistakable. He didn't crush the constructs. Instead, his free hand flickered with a brief, intricate spell—old, precise, carrying the weight of centuries. The eye and ear trembled, then folded in on themselves like paper caught in a sudden wind, collapsing into two small motes of light that winked out harmlessly.

The room felt cleaner. Lighter. The oppressive sensation of being observed vanished. Arto exhaled through his nose, shoulders dropping a fraction. He glanced at the notebook one last time, then reached over and closed it. The Stabilizer matrix he'd been refining earlier had been safely tucked into a separate, encrypted layer—nothing critical had been exposed.

Still… the watcher had been bold enough to probe a Gremory-secured channel and his personal workspace on the same night. That took skill. And guts. He shook his head once, a faint, wry smile tugging at his mouth. "Busy first week," he muttered to himself.

He turned off the lamp, leaving the room in darkness save for the soft moonlight filtering through the window before jumping on the bed, a sleep is in due after a long day.