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Three weeks had transformed Thane from a fortified village into something approaching a proper town.
The population had tripled. Goblin clans from the deeper forest had arrived seeking the protection of Lord Thanatos's walls. A tribe of lizardmen had migrated from the marshlands to the south after hearing about a monster nation that didn't operate on pure predation. Even some dwarven craftsmen had applied for residency, drawn by the promise of rare materials and steady work.
Which meant the walls had become inadequate.
Thanatos stood at the western edge of the settlement, one hand pressed against the diamond-stone barrier he'd created weeks ago. His magicules flowed through the structure, reading its dimensions, understanding its limits.
"Great Sage, calculate expansion requirements."
[Current population: 2,847. Projected population growth: 4,500 within two months based on current immigration rates. Recommended expansion: 60% increase in enclosed territory. New diameter: approximately 160 square miles.]
Thanatos closed his eyes and reached deeper into his Blood Dominion skill. The diamond walls weren't separate from him—they were extensions of his power, crystallized and made permanent. Expanding them was simply a matter of will and sufficient magicule investment.
He pushed.
The walls began to grow. Not violently—there was no cracking or breaking. They simply extended outward, the diamond core flowing like liquid before resolidifying, the stone layer following seamlessly. The expansion moved in a perfect circle, encompassing more forest, more clearings, the small lake to the south, and—
His Universal Sense caught it.
A leyline. A natural convergence point of magicules running beneath the western section of the newly claimed territory. Strong enough that it pulsed against his awareness like a second heartbeat.
Perfect.
The walls completed their expansion over the course of an hour. When Thanatos opened his eyes, Thane had grown significantly, and he had a new project location.
The Magic Tower took three days to construct.
It sat directly above the leyline, invisible to anyone who didn't know exactly where to look. Thanatos had created it from altered diamond—a variant he'd developed specifically for this purpose that didn't reflect or refract light. Instead, light passed through the structure as if it wasn't there, creating a perfect optical cloak.
Inside, the tower was seven stories tall, each floor dedicated to a different research focus. The top floor was his personal workshop, where he'd been spending most of his time lately.
Currently, that workshop contained three tables, each one holding a body.
Human spies. Caught by Touka's Red Order patrols over the past two weeks, trying to gather intelligence on Thane. They'd been interrogated thoroughly by Rimuru's people, then brought here for Thanatos's experiments.
Now they were dead. Very thoroughly dead, in ways that let Thanatos study exactly how souls separated from bodies.
"Great Sage, analysis of subject three?"
[Soul extraction successful. However, core quality remains unstable. The extracted essence contains magicules and elemental affinities as intended, but lacks the fundamental spark that defines true sapient soul structure. Classification: Pseudo-Soul. Unsuitable for Demon Lord evolution requirements.]
Thanatos looked down at the crystallized essence floating above the third body. It glowed faintly with mixed colors—earth affinity from one spy, fire from another, water from the third. He'd successfully fused their magicules and elemental properties into a single construct.
But it wasn't a real soul. It was components without consciousness, power without identity.
"The human soul requirement," Thanatos said. "Explain again why only human souls work for Demon Lord evolution."
[Human souls possess unlimited evolutionary potential. Unlike monster souls, which are locked into specific development paths determined by their race, human souls can adapt to any evolutionary direction. This flexibility makes them uniquely suitable as fuel for Demon Lord awakening. Monster souls, including those currently stored in Master's Underworld, cannot substitute for this requirement.]
So the seventeen thousand monster souls he'd accumulated from deaths across the Jura Forest were useless for his evolution. He needed ten thousand human souls specifically.
Which meant either a massacre of human settlements, or finding another way.
"Notice: Today is the scheduled date with subordinate Touka."
Thanatos stopped mid-thought. "What?"
[Master agreed to a date with Touka as reward for successfully completing the combat test against Geld. The date was scheduled for today at noon. Current time: 11:47 AM.]
"I forgot."
[Recommendation: Do not inform Touka of this fact.]
A knock at the tower's entrance—which shouldn't have been possible since the tower was invisible and the door was locked with blood-keyed wards.
Thanatos descended to the ground floor and opened the door to find Rimuru waiting outside.
"How did you find this place?"
"I'm connected to you through the Pact," Rimuru said. "I can always find you if I try hard enough. Also, you're about to be late for your date with Touka, and I'm here to make sure you don't accidentally stand her up by getting too absorbed in whatever disturbing experiments you're doing up there."
Thanatos glanced back at the tower. "I was making progress on soul research."
"You were literally about to forget about the date entirely, weren't you?"
"...Yes."
"Thanatos." Rimuru's tone shifted to something between exasperation and genuine concern. "You promised her. And more importantly—you're supposed to be a gentleman. At least make sure Touka enjoys herself."
"I don't know how to be a gentleman. I've never been on a date."
"Neither have I, but I've watched enough anime to fake it. Just... be nice. Pay attention to her. Don't talk about soul extraction or death energy. Pretend to be a normal person for a few hours."
Thanatos considered this. Then he looked down at his current outfit—practical black clothing designed for laboratory work, currently sporting minor blood stains.
"I need different clothes."
"Yes, you do."
Touka was waiting in the central plaza, and when Thanatos saw her, something in his chest tightened unexpectedly.
She wore a dress. Not armor, not her military uniform—an actual dress in deep blue that matched her hair, with white accents that caught the afternoon light. Her hair was down instead of tied back, falling past her shoulders in waves. She'd clearly put significant effort into her appearance.
She looked almost exactly like Touka Kirishima had looked on the rare occasions she'd dressed up in Tokyo. The resemblance was striking enough that for a moment, Thanatos forgot this wasn't actually her.
"Master Ken," Touka said, and there was a hint of nervousness in her voice that he'd never heard before. "You came."
"I promised I would." Thanatos activated his newly acquired Production Magic—a skill he'd gained through his experiments with matter manipulation—and concentrated. His clothing shifted, reorganizing itself into a proper black tuxedo with a crimson tie. Not perfect, but serviceable.
Touka's eyes widened slightly. "That's... impressive."
"Useful skill. Shall we?"
He offered his arm, and after a moment's hesitation, Touka took it.
Behind them, hidden behind a building corner and using Sticky Thread to cling to the wall, Rimuru watched with the intensity of a professional chaperone. This was going to be a long afternoon.
The date progressed through Thane's newly established entertainment district.
First stop: a restaurant that had opened just last week, run by a hobgoblin chef who'd migrated from the eastern territories. Thanatos had never actually eaten at a restaurant in this world—he usually just consumed whatever was convenient or nothing at all.
The food was surprisingly good. Touka talked about the Red Order's recent developments, about Geld's integration into the force, about her plans for training new recruits. Thanatos listened and let Great Sage run subtle scans on how her emotional state affected her soul wavelength.
[Notice: Subject's soul structure shows increased luminosity correlated with positive emotional responses. Wavelength becomes more stable and coherent when subject experiences contentment or happiness.]
Interesting. Emotions directly affected soul quality in measurable ways.
Second stop: an arcade that some enterprising goblins had built after Rimuru explained the concept from Earth. Primitive games compared to Tokyo standards, but creative. Touka was surprisingly competitive, which manifested in her absolutely crushing Thanatos at a game involving throwing projectiles at targets.
"You're very good at this," Thanatos observed.
"I've been training soldiers. Throwing accuracy is important." Touka smiled, and it was genuine rather than her usual professional expression. "Also, it's nice to beat you at something."
[Soul wavelength spike detected. Subject experiencing joy. Intensity: high.]
Third stop: a boat ride on the lake that the wall expansion had enclosed. One of the lizardmen tribes had started offering rides as a service, and Thanatos had to admit the lake was pleasant. Calm water, afternoon sun, quiet except for the gentle sound of the boat moving.
Touka sat across from him, looking out over the water.
"I never had time for things like this," she said quietly. "Before you found me, I mean. When I was just an Orc general trying to survive in an army that barely acknowledged I existed. Every day was fighting, struggling, proving myself over and over."
"And now?"
"Now I have purpose. Power. A lord worth serving." She looked at him. "You gave me a second life, Master Ken. One where I'm not defined by what I was, but by what I choose to become."
[Soul wavelength: extremely stable. Subject experiencing deep gratitude and loyalty. Additional element detected: emotional attachment beyond professional subordination.]
That was... concerning. Attachment was a liability. Emotions clouded judgment.
But it was also useful data.
Fourth stop: a garden that had been cultivated in the southeastern section of town. The ogres had taken it upon themselves to create a proper Japanese-style garden, and the result was impressive. Stone paths, carefully pruned trees, a small meditation pond.
They walked through it in comfortable silence. Touka seemed content just being present, and Thanatos was content letting Great Sage continue collecting soul data.
[Observation: Subject's soul is self-optimizing. Each positive experience incrementally improves soul structure coherence. Estimated growth rate: 0.3% improvement in soul quality per hour of sustained positive emotional state.]
So positive emotions literally improved soul quality. That was the data he'd been missing. If he could replicate this process artificially—
"Master Ken," Touka said, interrupting his thoughts. "Thank you. For all of this."
"You earned it."
"Still. Thank you." She paused at a bench overlooking the pond. "Can we sit?"
They sat. The sun was beginning to set, painting the sky in shades of orange and red.
"You know what the strangest part is?" Touka said. "I have memories that aren't mine. The naming process—it gave me fragments of someone else's life. Someone you knew before."
Thanatos went very still.
"I know her name was Touka. I know she worked at a coffee shop. I know she cared about you, even when you pushed her away." Touka looked at him. "I know I'm not her. I'm my own person. But sometimes I feel what she felt, and I understand why you chose that name."
"I didn't mean to transfer those memories," Thanatos said quietly.
"I know. But I'm glad you did." Touka leaned her head against his shoulder, a gesture that was probably influenced by those borrowed memories. "Because they help me understand you. And they help me understand what I want to be for you."
"Which is?"
"Someone you don't have to push away. Someone who can stand beside you without breaking. Someone who makes you stronger, not weaker."
[Warning: Subject's soul wavelength indicates extremely strong emotional attachment forming. This exceeds typical subordinate loyalty patterns. Classification: personal bond development.]
Touka's breathing slowed, becoming deeper and more regular. When Thanatos looked down, her eyes were closed, her expression peaceful.
She'd fallen asleep against his shoulder.
He sat there, watching the sunset, with a subordinate he'd created sleeping against him and data streaming through his mind about soul optimization through emotional bonds.
This was a problem.
She was supposed to be a tool. A powerful soldier in his army, nothing more. Tools didn't develop personal attachments. Tools didn't have dates or borrowed memories or fall asleep on your shoulder.
But she wasn't just a tool anymore, was she? She was a person. One he'd created, named, given power and purpose. One who looked at him like he was a hero instead of the monster he actually was.
He should correct that perception. Tell her the truth—that he'd brought back Geld just to test her abilities, that this date had been partly to study her soul structure, that everything he did was calculated toward gaining power.
He didn't.
Instead, he let her sleep, let the sunset fade, let the moment be what it was.
When full dark had fallen, he carefully created a blood construct beneath her—a stretcher that would carry her without waking her.
"Rimuru," he said to the darkness, knowing the slime was nearby.
Rimuru materialized from behind a tree, looking somewhat sheepish about being caught.
"Take her back to her quarters. Make sure she's comfortable."
"That was... actually sweet of you," Rimuru said, approaching the sleeping Touka.
"It was strategically sound. She's more loyal now, which makes her more effective."
"Sure. That's definitely the only reason." Rimuru used his Sticky Thread to carefully lift Touka onto his gelatinous body. "For what it's worth, I think she had a good time."
"Good. That was the objective."
Rimuru left, carrying Touka back toward the Red Order barracks.
Thanatos stayed on the bench, looking up at the stars.
"Great Sage," he said quietly. "Compile the soul data from today."
[Compilation complete. Key finding: Positive emotional experiences improve soul quality through increased coherence and stability. However, this process requires genuine emotional investment from subject. Artificial stimulation of positive emotions without corresponding genuine experience produces no measurable improvement.]
So he couldn't fake it. The emotions had to be real for the soul improvement to work.
Which meant his original plan—mass-producing souls through artificial means—was impossible. Souls required genuine experiences, genuine emotions, genuine development.
"New objective," Thanatos said. "Find alternative methods to acquire ten thousand human souls without requiring personal emotional investment."
[Acknowledged. Calculating options...]
He sat there under the stars, refusing to think about the fact that somewhere in his chest, something had stirred when he saw Touka in that dress. Refusing to acknowledge that letting her sleep on his shoulder had felt comfortable in a way nothing had felt since Tokyo.
This time, he couldn't let anyone close. Closeness was weakness. Attachment was liability.
Power was the only thing that mattered.
He repeated that to himself until he believed it.