After finishing his work that afternoon, Noah came to Bill's office.
He placed his hand on the doorknob and was just about to turn it when a sharp presence suddenly put him on alert, making him yank his hand back at once.
Thunk!
A sharp blade pierced straight through the door, its tip stopping right beside the handle.
Noah immediately took two steps back, his expression turning grave.
If he had failed to notice the killing intent from behind the door just now, or if his reaction had been even a little slower, his hand would have been skewered by that knife.
"This is… the fruit knife from the office?"
After appraising it, Noah found that the knife was one of the tools he was familiar with.
The one who had ambushed him had used something from the room itself rather than bringing a weapon of their own.
"Who's there?!"
He dropped into a combat stance, his attention fully focused on the pierced wood.
But the only answer was total silence.
The attacker made no further move. If not for the steel blade stabbed through the door, it would have been as though that attack never happened.
'Strange,' Noah thought.
Since the first strike failed, why didn't they immediately kick the door open and rush out?
Weren't they afraid he'd raise the alarm and bring armed reinforcements down on them?
This was a classified, underground bunker, and Bill's office had no windows.
There was no way to escape except through the front door.
It wouldn't be an exaggeration to say that whoever was hiding inside had no wings to fly with.
They were trapped.
"I'll only say this once. Surrender now and explain yourself," Noah called out, probing for a response.
He hadn't deliberately used magic to hide his approach, but for the person inside to detect his footsteps and calculate the distance to his hand so precisely, that person had to be a terrifyingly skilled veteran assassin.
Even through the heavy oak door, Noah could feel the astonishing, suffocating pressure coming from within.
That alone proved the enemy was strong.
Calling the standard security guards over would only send them to their deaths.
And because he was keeping a safe distance, he couldn't determine Bill's condition.
Whether the old scientist was tied up, unconscious, or already dead, he couldn't tell.
So he tried to lure the attacker into opening the door themselves.
But his words got no answer at all.
Noah frowned slightly.
"I see."
'In that case, brute force it is.'
He slipped a hand into the deep pocket of his white lab coat and pulled out a small hilt.
It looked like nothing more than the handle of a cheap pocket knife. Plain, unadorned, and totally unremarkable.
Yet, after Noah swung that plain little hilt through the air twice, two invisible, razor-sharp blades of highly compressed air shot straight at the door.
Whoosh!
The faint whistling sound made the smiling man hiding behind the door instantly change his expression.
He threw himself flat against the floor at once, lifting his head just enough to keep his eyes fixed on the gap torn into the thick wood by that unknown, invisible attack.
'It was aimed right at my neck?!'
'How the hell did he do that? From just that one failed sneak attack earlier, he figured out my exact height and calculated the level of my throat?!'
The man couldn't help feeling deeply impressed.
Because that kind of spatial awareness took an extremely high level of veteran skill.
Standing safely outside the door, Noah could tell that the vacuum blades hadn't killed the intruder.
They hadn't even landed a hit.
He called out, "That was just a warning shot. Let me make this clear in advance—I'm not incapable of hitting you through the wood."
Still pressed flat against the floorboards, the man let a bead of cold sweat roll down his cheek.
'Hahahahaa, That didn't sound like bluffing at all! So he deliberately spared me? What an arrogant little brat.'
"Hey, old man, you really did dig up one hell of a monster," the man turned his head and sighed at Bill, who was sitting calmly on his leather sofa drinking hot tea as if nothing were wrong.
That's right.
Bill looked exactly as he always did, seated leisurely on the sofa, enjoying a steaming cup of Earl Grey without the slightest sign of injury or disarray.
His expression was calm, though there was a hint of deep impatience in his eyes, as if he were being forced to watch a thoroughly uninteresting theater performance.
"Gozuki, Noah is my student. I don't care how interested you are in his strength, there's no way I'm handing over a brilliant scientist with limitless potential just so you can drag him to the mountains and train him into another disposable assassin."
As an old acquaintance, Bill had already seen right through Gozuki's intentions.
So before the assassin could even finish setting up his recruitment pitch, Bill rejected him outright.
"You really think highly of him," Gozuki gave a wry smile, pushing himself up off the floor.
Outside, seeing that the intruder still hadn't answered, Noah raised the plain hilt again.
"Then..."
His wrist slowly tilted downward—
—right then—
"Wait!"
Bang!
Under Gozuki's push, the damaged door burst apart, falling off its hinges.
Seeing the cut surfaces of the shattered wood—sliced as smooth as polished mirrors—even Gozuki felt a chill run down his spine.
What kind of weapon had done that? He had only sensed something coming just now, yet even paying close attention, his trained eyes still hadn't been able to see what the projectile was.
He looked at the boy standing several meters down the hall, but his eyes quickly locked onto the plain hilt in Noah's hand.
'A hilt? No blade in sight.'
'Could that invisible thing that flew over earlier really have been the blade itself?'
"Amazing, boy. Was that attack just now done with the little toy in your hand?" Gozuki deliberately stepped aside a little so Noah could see the unharmed Bill sitting behind him.
Seeing that, Noah understood the situation perfectly.
This was probably some sort of twisted combat test Bill had tacitly allowed.
With the door already cut to pieces, Noah no longer needed to open it and simply stepped over the wreckage, walking straight into the office.
He glanced at the unfamiliar white-haired man, then looked at Bill, wordlessly asking him to explain what exactly was going on.
But before Bill could explain the prank, his gaze stayed fixed on Noah's coat pocket.
"You've already refined the prototype this far?" Bill asked, his tone carrying obvious surprise.
He was asking about the vacuum blade.
After all, just a few days ago, he had seen the messy prototype himself.
Back then, it had been nowhere near this lethal. Its attack range had been too short, its cutting power too weak, and the attacks too violently scattered to aim properly.
With so many flaws, Bill had thought this young student of his would soon wake up from his weapon-crafting fantasy and settle down into the field of human-body modification where he belonged.
But instead, Noah had created the gravity rings—weighted, mechanical equipment that drastically improved physical training.
And now, only a few days later, that crude useless hilt had already been improved to the point that it could threaten a seasoned veteran like Gozuki.
Gozuki was one of the Four Rakshasa Demons.
One of the Empire's top-tier martial arts experts.
"Mm, but there are still a few serious issues," Noah said, taking out the hilt and setting it on the tea table.
"The main problem lies with the Danger Beast used as the biological material. The wind organ of this specific species—the Kamaitachi—is far too fragile. Just like the beast itself, this artificial blade has awful endurance. It'll break after maybe eight or ten heavy swings at most. An authentic Imperial Arm wouldn't break that easily, so this thing can only count as a cheap consumable."
After that brief technical comment, Noah added seriously, "It's a raw material issue. The Danger Beast used for the core is simply too weak. I need to harvest something stronger."
The Danger Beast known as the Kamaitachi was a creature that lurked in deep forests, easily startled by even the smallest sound.
Once provoked, it turned vicious and used a natural "oscillator" organ inside its body to compress air into tiny vacuum blades, attacking intruders or prey from a distance.
Its victims ended up looking as though they had been cut down by invisible swords.
As Danger Beasts went, it was only a low-tier threat, hovering somewhere between Class Three and Class Four.
The Kamaitachi's natural ability to generate air blades couldn't really be called a true supernatural power.
It was just a low-efficiency energy conversion achieved through the unique biological organ in its throat.
Noah's hilt solved the mechanical efficiency problem of that energy conversion, drastically increasing the lethal power of the vacuum blades, but it still couldn't fix the flaw of their poor durability.
And while the vacuum blades were certainly fast and perfectly hidden, they still hadn't reached the point of being able to cleanly cut through thick steel armor.
If a knight blocked with a heavy iron sword, the vacuum blade would at most leave a deep, clear mark on the surface of the steel, but it wouldn't slice all the way through.
That level of cutting power, however, was already more than enough for killing unarmored targets.
The human body was much more fragile than steel, after all. Killing someone didn't require cutting them clean in half like a log.
As long as the invisible strike landed on a vital point like the throat, one blow was enough.
"Wait, what the hell are you two even talking about? This weapon was made from a harvested Danger Beast?" Gozuki stared at the hilt on the tea table in deep disbelief.
From his angle, it looked no different from the handle of an ordinary fruit knife—except that it had no steel blade.
'So that terrifying, invisible attack just now came from this little thing?'
'And the one who actually built it was this young boy?'
Noah glanced at the unfamiliar man.
Since Bill hadn't interrupted him and let him keep talking, that meant there was no need to keep any of the weapon's specs a secret from him.
'Gozuki,' Noah thought, matching the face to the files he read.
'So he's the head of the Empire's new elite assassination corps.'
'I see.'
Besides being the commander of the Scientific Corps, Bill also held an advisory post in the assassination corps.
He wore multiple hats for the Empire.
The two men's primary military positions were equal in rank, which meant they weren't superior and subordinate, but respected colleagues.
"Kamaitachi, huh? Now that you mention it, the attack did resemble a wild one. But the cutting power was clearly much greater than the natural beast," Gozuki muttered, staring at the hilt on the tea table, his eyes burning with greed.
This weapon was perfectly designed for high-level assassination!
It was easy to conceal in a pocket and wasn't something that drew suspicion from city guards.
Even if it were discovered during a pat-down, the lack of a sharp blade made it easy to explain away as a broken tool or a toy.
It was blindingly fast, nearly silent, could attack unexpectedly through cover, and possessed lethal range.
This thing was an incredible asset.
Seeing how interested the assassin was, Noah didn't hold back and explained the specs. "I made a few mechanical improvements to the biological core. I increased the cutting power to 3.3 times that of the Kamaitachi's own natural attack, and extended the effective kill range to exactly 12.5 meters."
"Can I try it?" Gozuki asked Bill first, respecting boundaries.
But Bill didn't answer.
He simply continued sipping his hot tea.
The assassin immediately understood the message.
Bill wasn't the one who built it. So he turned to Noah and asked again, "Kid, can you let me try this blade?"
Noah bent down, picked up the hilt from the tea table, and handed it over.
Taking the hilt, Gozuki couldn't help curling his lips upward into a dangerous smile.
"The safety switch on the side of the hilt is also the manual compression trigger," Noah instructed briefly.
"Once activated, the core starts absorbing and compressing ambient air. Swing it hard, and it'll release the blade."
"I see." Gozuki nodded, testing the grip.
The hilt was seamless, with only the small safety switch protruding slightly.
It was incredibly simple in design, but devastating in effect.
He liked weapons like that. No flashy nonsense.
He flipped the safety on. The sensation of rushing air being violently drawn into the hilt was obvious, creating a low, humming vibration in his palm.
After a short, three-second compression period, Gozuki raised the hilt and slashed brutally through the empty air in front of him.
Since there wasn't really a good target inside the pristine office, he aimed directly at the heavy oak door that had already been chopped to pieces.
In an instant, the veteran's arm almost seemed to vanish, leaving only crisscrossing, blurry afterimages in the air.
In the blink of an eye, he had already swung the hilt several times.
The invisible wind blades swept past Noah's face.
This time, the heavy wooden door panels were cut completely apart, reduced to a pile of splintered wreckage on the floor.
As the one who had personally unleashed the strike, Gozuki was deeply impressed.
'Amazing.'
'No—this is incredibly dangerous.'
'With this cheap, disposable tool in hand, even a weak untrained child could easily assassinate an adult three times stronger than themselves.'
'It cut through such a thick, solid door without making any loud noise at all.'
'That level of lethal concealment was truly... insane.'
It was terrifying.
Invisible, silent, and it would not even stain the wielder with blood.
Seeing the burning look in Gozuki's eyes, Bill could not help reminding him, "Gozuki, you haven't forgotten your original purpose, have you? Talk business first."
Gozuki reluctantly set down the hilt in his hand.
"Right."
It was time to discuss the real matter.
Gozuki's tall, slender frame sat on the sofa, looking somewhat cramped, but the aura around him suddenly grew sharper.
"Then, although this is business, the person I'm looking for hasn't changed. Noah, I came here for you."
Noah looked at him without the slightest change in expression.
He did not ask anything, because the other party would probably explain the reason next.
Still, the head of the Empire's assassination unit had come for him?
There were only so many possibilities.
"I won't hide it from you. I am the commander of the Empire's assassination unit."
"Oh."
What did he mean, "oh"?
That was his only reaction?
Gozuki deliberately released a trace of killing intent and pressed him further.
"You're not afraid?"
"Why?"
"Mm?"
"Why should I be afraid?" Noah asked in return. "I haven't done anything harmful to the Empire, nor do I remember offending any important figures. Even the Empire's assassination unit is still just a department of the Empire, isn't it? Civil servants, basically."
Civil servants?
Gozuki froze for a moment, then burst into laughter.
"Hahahahaha! Interesting. Very interesting."
Indeed, as long as someone had not done anything worthy of assassination, the Empire's assassination unit was merely one department of the Empire.
It would not act without authorization.
But even if people understood that clearly, when they stood face-to-face with an executioner who had killed countless people, when they smelled that stench of blood and despair, they would still inevitably panic and feel fear.
Yet none of that appeared on this boy at all.