The Assassin Clan's Hidden Vaults

The path underground lay deeper inside the study.

There was a sequence to it—pull the books in the proper order, then channel mana according to a unique pattern that shifted every day. Only then would the door respond. Working from Yashiro Tsugumi’s memories, I manipulated each step one by one. The bookcase slid open to either side, revealing an elevator that looked nothing like the traditional Japanese manor around it—pure science-fiction chrome and sleek lines.

What impressed me most was the thoroughness. Even if someone somehow forced the entrance open, the machine itself would refuse to move unless the user carried the blood of the Yashiro main family.

I drew out Yashiro Tsugumi’s soul and breathed mana into it. The energy converted itself with perfect naturalness, flowing out as mana that was no longer mine. It was a refined version of the method the chimera had used to filter and wield Shirogane Ichiro’s mana.

My own mana had always excelled at creation—at taking something that already existed, imitating it, and rebuilding it as my own. That talent only grew sharper; it never dulled. If I felt like it, I could even mimic a person’s very presence. I simply found the effort tedious and out of character, so I never bothered.

Click. Whoosh—

The door recognized Yashiro Tsugumi’s mana and opened.

The interior was sparse, without a single button or control panel. Operation required only the peculiar mana unique to the main family. Since the elevator only ever descended to one floor, there was no need for choices. I layered more of that converted mana around my body until the machine accepted me as Yashiro Tsugumi.

That alone was enough. The elevator began its descent of its own accord. I had already sent Hive ahead the moment I learned of the underground, and nothing truly threatening had turned up.

Everyone below was either a child or a raw recruit not yet fully accepted into the Yashiro ranks. I had business with them as well, but the real prize was the clan’s secret manuals. Handing them over to Lee Se-rin would be pointless—she already knew everything—so I decided to claim them myself.

If I could graft this world’s unique assassination techniques onto Ea, so much the better. And if the little girl Tsugumi had wanted to protect proved willing, teaching her those arts wouldn’t be a bad idea either. Only if she wanted it, of course.

After the coup and the subsequent slaughter of everyone left standing, the sole legitimate heir of pure Yashiro blood was now Shirogane Hanabi. She would cooperate with me completely from now on, so showing her the manuals would raise no eyebrows. It would also strengthen our forces. As a mother who had already raised two children, she would make an excellent teacher. Perfect material for cultivating the next generation—whatever her personality, her skill was beyond question.

Scattered bloodlines might still exist somewhere, but even if they tried to claim legitimacy, what could they possibly do once the Yashiro name rested in Lee Se-rin’s hands? For all I knew, any such survivors were already pieces she had prepared.

“The interior’s cleaner than I expected.”

I had pictured a gloomy cave, but this was the twenty-first century edging toward the twenty-second. The corridor was modern, almost cutting-edge. True to an assassin clan’s nature, it clung stubbornly to the principle of no scent, no flavor, no presence.

That principle did not last long. With every step the smell of blood grew thicker. I could sense people gathered beyond. The child Tsugumi had spoken of was almost certainly there; his soul had already begun to stir restlessly inside me.

I walked past without a glance. Timing mattered. Taking the girl out would be the very last step. First I would collect everything worth taking, then leave at my leisure.

“Here it is.”

The most ordinary-looking door in the entire space. In a place like this, “ordinary” was simply another word for “most dangerous.”

I did not open it at once. Instead I stirred my mana in front of it. One second, two… after roughly ten seconds the door opened on its own.

A robot stood inside. Unlike Comet’s sleek android form, this one made no effort to hide its mechanical nature. It wore a tailcoat that clashed absurdly ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠with its frame, as though a machine were clumsily play-acting at being human.

Did the costume serve any purpose? None whatsoever. Pure bad taste. According to Tsugumi’s memories it had been built that way to honor the will of the first Yashiro’s attendant, but to my eyes it simply looked half-finished.

Having awakened to the power of creation, I found such crude workmanship instinctively irritating—like watching a half-trained amateur show off in front of a specialist.

“Unpleasant.”

The machine sagged slightly, radiating disappointment, and stepped back two paces. I snorted. To someone who could see souls, that drooping posture was ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠pure deception. There was no soul inside it—not even a convincing imitation. Only complex circuitry. A product of meticulously written programs, nothing more.

Its quality was inferior even to Comet’s, and lower still than the Guardians stationed at the Academy. The construction was similar yet subtly alien; someone had clearly stolen the original designs meant for the Academy Guardians and remade them into this form. The original creator’s permission? Who cared? They had simply locked the things away in a place no ordinary person could ever reach, so the creator would never know. That must have been the thinking.

Comet, reading my thoughts through the Link, bristled with competitive indignation. What was this? Was she claiming that one servant was enough for me—herself? And what about the other summons? Ah, right: they weren’t servants, so they didn’t count. Ridiculous. Yet I couldn’t even work up real exasperation. It was like watching a child throw a tantrum right in front of me—more amusing than anything.

She never used to act this way, which only made the change more striking. Her sense of self had solidified further. The full opening of my class was clearly affecting the summons linked to me as well.

Comet had been built for human service from the start, so her growth was simply more colorful. Given time, the others would reach the same level of communication.

The most promising candidates… Kallion and Shiz, I suppose.

Intelligence stats mattered, but their racial advantages towered over the rest. Their growth ceilings had been vast from the beginning, so even when they leveled alongside the others, they pulled ahead faster. Shiz, whose role was to guide souls that had once been human, inevitably grew closer to humanity simply by proximity.

Of course evolution would let the others break their original racial limits as well. This was only a prediction for now.

The chamber holding the secret manuals resembled a library—an extremely old one. Not only Yashiro techniques, but ancient histories and the stolen manuals of every clan the Yashiro had absorbed over the centuries would be stored here.

I ordered Hive and Haze to collect every last volume.

“…!!!”

Hive’s eyes sparkled with uncharacteristic excitement. He even split into clones, wrapping the books in shadow and sweeping them away. Haze produced a sighing emoticon at the sight, then methodically teleported the books from the upper shelves down into Hive’s shadows one by one.

Come to think of it, these manuals would be useful for Hive as well—not just Ea. Hive could already mimic human shadows; adding variety to his numbers would expand his tactical options even further.

Nice.

They were seeking out their own shortcomings and growing without waiting for my orders, all so they could prove themselves to me. Pride welled up unbidden. Taking the long road after the easy early path had been worth it after all.

Once the vast cavern had been emptied of every book, I spread my mana more carefully. These people were the type to leave traps. There was no way the true manuals would be sitting out in the open like that.

With Haze’s help the shadows found an empty space that registered as completely blank—yet was clearly hollow.

Bingo.

I shaped my mana, layered in the principle of One Line, and sliced the wall clean away.

Crunch!!

The machine that had begun to speak and fire hidden weapons from its launch ports was swallowed whole by the maw of a massive shadow beast Hive had formed. It sank into the darkness without a sound. That technique was originally Ea’s specialty; Hive must have watched and learned. Scary kid.

It also meant Ea’s performance in the earlier battle had left a deep impression. She had stayed out of sight, yet every time someone inside the building tried anything, she had assassinated them all. Sabotage and psychological warfare still needed work, but when it came to pure killing, Ea was already close to complete. All those goblins I had forced her to slaughter had paid off.

“Let’s see…”

The chamber beyond held an altar so gloomy it could only belong to an assassin clan. Atop it lay objects of extreme age—wooden tablets, hanji paper, bamboo strips, fired clay, paintings, and more. I took the entire altar and everything on it. With things like this, half-measures only left loose ends.

I looted three more similar caches, then swept the entire space with mana to make certain nothing had been missed.

The storerooms held little of value. Weapon forging was handled elsewhere, so there were no worthwhile byproducts—only finished weapons left to gather dust and potions and elixirs stored as inventory. The only truly useful items were the recovery potions.

From Hisame’s and Tsugumi’s memories I already knew how inefficient their training was. The stated purpose—hardening them against pain so that even if captured they would never reveal Yashiro secrets—sounded reasonable. In reality it was simply torture dressed up as training, a way for the instructors to indulge their own twisted desires. Beating someone repeatedly with no instruction was not training.

Of course, after the “training” they needed high-grade potions or healers on standby to deal with the aftermath. No one who practiced the noble art of healing would willingly take part in such inhumanity, and hiring individuals one by one was troublesome, so they naturally leaned toward medicine. Their traditional skill with toxins meant the recovery potions they produced were of remarkably high quality—flawed, however, by a critical side effect: extreme regenerative power purchased at the cost of slowed cellular activity.

That drawback was severe. The most obvious consequence was delayed natural healing. Cells that should die and regenerate rapidly instead lingered long past their usefulness. The body, sensing sufficient cell count, stopped producing new ones. Over time the system evolved to believe rapid cell production was unnecessary. When true need arose, regeneration lagged. Wounds that should have closed continued to tear open and fester; blood refused to clot. The result was a body that bruised easily, fell ill easily, and eventually failed in other functions as well.

Mana could suppress the tendency to some degree, but anyone without mana would be crippled in short order. Yashiro training was not designed to forge the weak into the strong. It was designed to find those who were already destined to be strong by ensuring only the strong survived.

Under normal circumstances such a method should have wiped the clan out generations ago. The problem was that this world was insane enough for the method to work. More importantly, the Yashiro bloodline—specialized in “protection”—was simply that excellent, allowing them to endure what should have been lethal.

In that light I finally understood why they had wanted Shirogane Hanabi so badly. She was regarded as the reincarnation of the first Yashiro. Using her as a breeding mother to cross with superior bloodlines might produce someone even greater than the founder. That had been their calculation. And when the union of Hanabi and Shirogane Ichiro—famous for forging weapons inside blazing forges—produced the overwhelming anomaly that was Shirogane Rui, the theory had become certainty.

Knowing the full story, I could also dimly grasp why Tsugumi had been so obsessively protective of that particular child. In training where the incompetent could not survive, she had survived while remaining incompetent. Weak and incomplete, yet desperately clinging to life—that brightness was enough to captivate anyone living in darkness.

“Tch…”

Which only made things more troublesome.

Every event has a cause. Where there is a result, a reason must exist. An incompetent child surviving training that kills the incompetent? Nonsense. If she were truly talentless she could never have lived. She possessed talent—whether she herself was ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠unaware of it or deliberately hid it remained to be seen.

What mattered was her will.

I retraced my steps without bothering to conceal my presence. Instead I unleashed it, crushing everything under sheer pressure. When I reached the blood-reeking door I condensed my aura for an instant, creating the illusion that some vast existence had arrived and then vanished. The moment concentration inside shattered and their auras wavered, I kicked the door in.

KRAAAAAANG!!!!

Even without mana my stats were high enough to smash a door like this with ease—especially now that Subjugator had risen to level 3 and its growth bonus had jumped from 200 to 300. At my current strength I could probably crumple a C-rank dungeon boss with raw power alone. With Battle King assisting, combat-limited strength would climb even higher.

The room beyond was spacious. Clean enough to resemble a facility, yet the lingering stench of blood ruined the image. Boys and girls had been separated into glass-fronted cells like animals in a pet shop. The sight was nauseating. In my previous life there had been people who tried to raise humans this way—mostly the wealthy. As if they had known the end was coming, they stockpiled everything and built an entire underground city, a second Earth. There they became gods. With the world ending, morality no longer applied; the limiter snapped. People became livestock. The slave class became entertainment for the noble class. Some killed for fun. Some raped and watched at leisure. Some raised humans as pets.

Even with a brain reshaped by research, those scenes had still made me sick. So I had slaughtered every last one of them—slave and noble alike—without distinction. A dying world had no reason left to live. Once beings that could be called human disappeared, the future vanished with them. I cleaned house as a small act of atonement, so the world could at least end a little cleaner.

I had changed, yet I had not changed.

Therefore I would offer a choice. I spread my aura. Those who had fled to the corners of the room looked wretched. The ones who had already received some training immediately turned hostile, yet their stronger instinct to live made them flinch away.

Among them I found a black-haired girl trembling with fear yet still approaching the glass, staring at me with a vacant expression. I looked down at her.

I interfered with the molecular structure of the glass. A light tap reduced it to sand, as though it had never been solid. The girl, her support gone, collapsed to her knees.

They must have tortured her before I arrived. Her body shook violently; scabs of dried blood dotted her skin.

“…Prince…?”

Her eyes were unfocused, projecting someone else’s face onto mine. She looked about ten years old. Fairy tales or some equivalent delusion, no doubt.

I did not allow it. Shadows forced her upright. Pain twisted her face; tears welled. The forced movement registered as an attack, so the effects of Sadism and Torture nested inside Reaper stacked on top. She was feeling at least twice the agony she was used to. That should clear her head.

I used the shadows to tilt her face upward, then removed my mask so our eyes could meet. I needed a clearer look.

The soul inside her was far too pure for a place like this—and at the same time so bright it felt alien, ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠as though she had armored herself with light because she had no other choice.

A skill.

I didn’t know what it was, but some power was clearly involved. I dug deeper, scrutinizing her without mercy. My reflection appeared in her black pupils—dragon-like slit pupils of deep crimson, and within them a colorless flame that observed souls.

In the endless mirror of eye meeting eye I discovered two souls residing inside the child. Or rather, two that had already fused into one. Suspicious, but I set the question aside for now.

“Choose.”

Die comfortably here, or live in this insane world and prove yourself.

Her eyes trembled. Conflict—brief, intense—then she squeezed them shut. When she opened them again her expression had grown calm, almost detached, carrying a wisdom that did not belong on a child’s face.

“The uncle told me… if I stayed good, I would definitely get out. That someone would come to help me leave. Are you the person the uncle talked about, big brother?”

“No.”

“…Then what happened to the uncle?”

“I killed him.”

She did not ask “who.” She simply exhaled a long, empty sigh—mourning Tsugumi’s death, or perhaps complaining that I had killed the man she had carefully prepared as her ticket out. Maybe she was simply hit by the realization that his useless death had dropped her into an even more dangerous situation.

…Was that too cynical?

It didn’t matter. Either way, the girl in front of me felt distinctly different from the child of a moment ago—enough to create a sense of wrongness. That strangeness must have been what drew Tsugumi’s eye.

“…Please save me.”

“All right.”

She begged. I accepted. That had been the condition from the start. The agreement seemed to surprise her; her eyes flew wide before she hastily composed her face. I ignored it, tapped the floor, and had Hive form a humanoid shadow to carry her.

Then I looked at the other children who were beginning to kindle fragile hope at the sight, and raised my mana.

“We’re leaving.”

I didn’t need much. None of them could block me.

KRUDDDDK!!

Shadows erupted from the floor in an instant, devouring every life without remainder. I sorted the freed souls and handed them to Hive. That was all.

Dozens of children became a handful of orbs. End of story.

A moment later Keres’s flames rose, incinerating the leftover corpses so that no soul fragments remained.

“…Huh?”

Even the strange girl found the unreal spectacle beyond her limits. Her face went from blue to pure white; she began to tremble violently. Then she clamped both hands over her mouth—not from nausea, but because she refused to scream and risk displeasing me.

I would have to thank Tsugumi properly. He was already dead and had nothing left but to serve me, yet I decided to pour a little extra care into him.

And perhaps run a small test. I couldn’t guarantee my own case was unique.

“You really are abnormal. Is it because two souls have merged?”

The words shook her harder than the massacre she had just witnessed. Then her consciousness simply cut out—like a fuse forcibly blown. Overload. She went limp as dried squid and was transferred into Hive’s shadow. I watched without expression and pulled my mask back on.

Cleanup was finished.

No one left alive. Still, just in case, I left a few of Hive’s surveillance shadows behind, recalled the rest, and completely withdrew the mana that had saturated the area. Only then did the faint dizziness and lingering discomfort vanish. Forcing my body to keep moving through its disharmony had been more exhausting than expected.

The rest I would leave to Lee Se-rin.

I asked Haze to tear open space, then stepped toward the rift.