Hiruko Kohina
****
"Hahahahahahaha!!"
The sudden, sharp laugh sliced through the tense air of the conference room like a blade, halting Tendo Kisara mid-sentence as she questioned Seitenshi about the mysterious box. Every president seated around the oval table froze, their thoughts shattered by the interruption.
Dozens of eyes darted toward the source of the sound—and widened in shock.
In the seat that had been empty just moments before, a masked man now sat with his polished black shoes propped arrogantly on the table. His outfit looked straight out of a magician's act: a top hat, white gloves, a dark tailcoat. He straightened up with an almost theatrical flourish, laughter echoing around him.
The masked man hopped lightly onto the tabletop, as if floating, his steps utterly disrespectful as he strolled to the center of the long table. Facing the monitor that displayed Seitenshi's image, he stopped and bowed deeply, removing his hat like some refined noble.
"State your name."
"Excuse me." His voice carried a mocking politeness. "My name is Hiruko… Hiruko Kagetane. A pleasure to finally meet you, oh incompetent head of state."
The mockery dripped like poison from every syllable. "To be blunt, I am your enemy."
Seitenshi's expression hardened instantly, lips pressing into a thin line. Whether from being openly insulted, or from this brazen man declaring himself an enemy in front of the Ministry, no one could tell.
"…A full-body Mechanical Transformation, huh?"
The quiet voice belonged to Yotsuba Mahiro. His sharp eyes scanned the masked man like he was sizing up a new toy. Hiruko Kagetane… of course Mahiro remembered that name.
Like Rentaro, he was once part of the 787th Mechanized Special Forces of the Ground Self-Defense Force's Eastern Army. But the difference was staggering—while Rentaro had only replaced a leg, an arm, and an eye with hyper-titanium prosthetics, this man had gone much further. His entire body—his organs, his frame—everything had been replaced.
It was less human augmentation and more like mechanical ascension.
Was this also one of Muroto-sensei's "masterpieces"? Mahiro wondered, lips quirking ever so slightly.
Before he could ponder further, Hiruko snapped his fingers.
From the shadows emerged a girl—small, delicate in stature, with short, wavy dark-green hair. She wore a black frilled dress, her pale hands resting on the table as she clambered onto it with a quick "Heh-shoo!" and hurried to Hiruko's side.
The girl pinched the hem of her skirt and bowed neatly.
"My name is Hiruko Kohina, ten years old."
Two slender titanium katanas hung crossed at her lower back, their blades still dripping with blood. A dangerous gleam shone in her eyes.
Mahiro's expression didn't change, but inwardly he recalled who she was. A broken child—brainwashed since birth by Hiruko Kagetane, raised not as a girl but as a blade.
The air grew heavy. Hiruko's mocking introduction alone had shattered the room's composure, but when he uttered the words "Legacy of the Seven Stars," the atmosphere twisted further. Faces turned grim. Everyone present knew what that meant.
(The box)
Tension snapped like glass, and chaos erupted.
"Open fire!!"
Bullets blazed through the air toward Hiruko Kagetane, but the man only chuckled. Spreading his arms wide, a rippling, radial field expanded outward from him. Bullets halted mid-flight, frozen as though the very laws of physics bent at his whim. Then—like a cruel joke—they ricocheted, returning to their shooters.
"Gyaaah!!"
"Ughhh!"
Screams filled the conference chamber. Several IFAs collapsed, blood seeping from fresh wounds. Others dove behind the oval table, but nowhere was truly safe.
Mahiro didn't hesitate. With calm precision, he stepped forward, shielding Kisara and Asaka-chan behind him, dispersing incoming stray bullets as if brushing away sparks from a fire.
The acrid stench of gunpowder thickened in the air, mingling with cries of pain. The once-pristine conference room was now chaos—smoke curling upward, walls peppered with dents from gunfire.
"Oh my, oh my… looks like not all IFAs are useless, huh?" Hiruko's voice purred, directed toward Mahiro. "The proud lone wolf, Mahiro-kun."
Dozens of gazes shifted. Even Seitenshi, her composure strained, leaned forward slightly at the monitor. To her, this boy might be the only one who could shift the situation.
"Mr. Mahiro," Seitenshi spoke firmly, her voice ringing across the monitors, "please… take down this madman."
Mahiro's sharp eyes slid toward her. He didn't answer immediately. Instead, he tilted his head slightly, his voice calm, almost casual:
"No problem with taking action. But… what's the reward?"
"One-tenth of the mission's reward. One hundred million yen."
"No problem," Mahiro replied smoothly, his lips twitching in the faintest of smirks. "But that loli… and any drops afterward—they belong to me."
"…What?" Seitenshi blinked, clearly confused by his phrasing. But pressed for time, she simply nodded. "Fine. Agreed."
That was all Mahiro needed.
With an almost bored air, he stepped onto the oval table. The dull thuds of his shoes echoed across the chamber, each step beating against the hearts of everyone watching.
His posture, his arrogance—it was the same brazen disregard Hiruko had shown earlier.
"Mahiro-kun, be careful!" Kisara's voice rang out, almost trembling.
"It's nothing," Mahiro replied, flashing her a faint smile. "Just a mere modified soldier."
From his pocket, he drew out a strange, pitch-black weapon. It looked like a handgun at first glance, but the design was too alien—flat-barreled, with no visible chamber for bullets.
Hiruko's masked face tilted slightly. Then he laughed, spreading his arms as though welcoming the world.
"Oh my, oh my… Mr. Yotsuba Mahiro is truly arrogant! Guns cannot pierce my Imaginary Gimmick."
He gestured grandly, inviting Mahiro to fire at will.
Mahiro's eyes narrowed. "Is that so? Then let's test it."
Inside the Holy Residence, far away, the old man Kikunojo Tendo—advisor to Seitenshi—suddenly felt a chill run down his spine. His instincts screamed at him.
"IFA Yotsuba Mahiro!!" he shouted into the comms, his voice cracking with urgency. "Capture Hiruko Kagetane alive! He possesses information vital to the Holy Residence!"
By the time Kikunojo Tendo shouted that command, it was already far too late.
Because Yotsuba Mahiro had already pulled the trigger.
Scattering Mist—activated!
"Ugh…!"
Beneath the mask, Hiruko Kagetane's eyes widened in shock. His hand clutched at his chest, fingers digging into the fabric of his suit as though he were struggling to contain something violent tearing him apart from the inside. For a brief second, it looked like he was enduring unbearable pain, his proud posture trembling.
But that second didn't last.
"D-Did he just… disappear…?" one of the IFAs gasped in disbelief.
The entire conference chamber froze. The gunfire had stopped, groans of the injured fell silent, and even the acrid scent of gunpowder seemed less noticeable compared to the shock flooding their senses. Their jaws fell open. The invincible enemy who shrugged off bullets, who bent reality itself with his repulsive field—Hiruko Kagetane—was gone.
Not merely slain. Not merely defeated.
Evaporated.
Yes… literally evaporated before their eyes.
Kagetane's body decomposed at the elemental level, vanishing in a haze of shimmering flame and smoke. Organic matter unraveled: proteins breaking into hydrogen, oxygen, nitrogen, carbon; bone shattering into calcium, phosphorus, and trace minerals. Even his blood and nerves dissolved into fundamental ions before dispersing into the air.
The lighter gases, like hydrogen, lifted and dissipated soundlessly. Others, mixed with oxygen, combusted in faint sparks before fading out. To the stunned audience, all they saw was the masked man's form collapsing into a drifting haze of fire that melted away into nothing.
What remained behind was not a corpse, not even ashes—only a clatter of cold, gleaming parts.
Hyper-titanium alloy components—his prosthetic organs, his cybernetic heart, his modified lungs—all useless now, still faintly humming with heat as they lost the biological signals that had once powered them.
Mahiro stepped forward through the haze, calm as always. He crouched, picked up the scattered mechanical organs, and turned them in his hands with the quiet curiosity of a craftsman inspecting raw material.
"Not bad," he murmured. "First time doing multi-level decomposition at this scale, but… seems like it worked out fine."
Like pulling a rabbit out of a magician's hat, he flicked his wrist and stowed the parts into his storage ring, already planning to deliver them to Tatsuya and the FLT labs for research. Who knew? Perhaps these scraps would birth something new, something dangerous, something useful.
"D-Daddy… Daddy! Where are you?!"
A trembling, high-pitched cry broke the silence. Hiruko Kohina, the little girl who had stood so proudly at her father's side just moments ago, now collapsed to her knees on the table. Her crimson eyes darted wildly as her hands clawed desperately through the scattered dust, trying to grasp something—anything—that might prove her father still existed.
Her lips quivered, muttering his name like a charm that could summon him back. But all her fingertips found was gray powder and the cold wooden surface of the table.
Until—
"Daddy?!" Her eyes lit up. She had touched the tip of a boot. Her gaze shot upward.
But instead of her father's masked face, she met the composed, almost indifferent expression of Yotsuba Mahiro.
"Hiruko Kagetane is dead," Mahiro said flatly, like reciting a fact from a textbook.
"Impossible!" Kohina shrieked, her voice breaking. Tears welled in her eyes, trembling but burning with fury. "You're lying! Daddy's the strongest! He can't be defeated by the likes of you! I'll cut you… I'll cut you… I'LL CUT YOU!!!"
Her body convulsed like a beast driven insane. With a scream, she drew her dual katanas, the steel gleaming, and slashed them across in a furious cross-cut aimed at Mahiro's waist.
Clang!
A spray of sparks burst through the air.
"Don't be so rude to Mahiro-sama! Your opponent is me!"
Asaka Mibu's voice rang out sharply as she appeared between them, her blade intercepting Kohina's furious strike. Sparks cascaded between their faces, lighting their eyes with a fierce glow.
Before Kohina could recover, Asaka thrust her foot into the younger girl's stomach, sending her flying back across the table. The blow knocked the wind out of her, scattering her movements.
Mahiro's hand had already drifted toward his CAD, ready to end the fight in an instant, but he paused. Watching Asaka stand firm, her sword raised, he instead let his hand fall back to his side.
…Yes, this was fine.
Let Asaka fight. Let her test the results of her training.
After all, Asaka had trained in kendo under Tendo Kisara for a year now. Her skill was far sharper than before. Purely in swordsmanship, she had already surpassed the ranking Kohina once boasted of. Mahiro knew it—and Asaka herself seemed determined to prove it.
Perhaps this battle was not about Kohina anymore. Perhaps it was about Asaka testing her blade… and venting the jealousy and frustrations she had quietly bottled up.
"Do you understand what you've done, IFA Yotsuba Mahiro?!"
A roar thundered across the room from the screen. Kikunojo Tendo's weathered face was livid, his sharp eyes burning with anger.
Mahiro turned casually toward the screen, feigning a confused look, his tone dripping with false innocence.
"What did I do? I just eliminated a terrorist, as requested by Seitenshi herself. Was that wrong?"
"….."
Kikunojo's chest rose and fell with restrained fury, his gaze narrowing, sharp enough to pierce the monitor itself.
"That man carried vital intelligence. Information crucial to the Holy Residence!"
"Oh really? Then why didn't you say so earlier?"
Yotsuba Mahiro's voice carried across the ruined conference room, light but sharp, mocking as he spread his arms dramatically. His gaze fixed on the old man displayed on the massive screen. "Besides… isn't that your higher-ups' business? What does it have to do with me, an IFA? Don't tell me, Mr. Tendo Aide… you're trying to back out of the payment?"
The final words carried weight, his mocking tone layered with the quiet but unmistakable edge of a threat.
"That's right," Mahiro continued, his lips curving in a faint smirk. "Whatever information Hiruko Kagetane carried has nothing to do with us IFAs. If you want to blame anyone, blame yourselves for not clearly stating the commission terms from the beginning."
At that moment, footsteps echoed against the battered conference table. Everyone turned their heads. Kisara—calm, graceful, yet with an air of icy hatred—was walking step by step toward the massive display. Her small frame seemed to dominate the room as her sharp eyes locked onto Kikunojo Tendo.
"Kisara…" Mahiro murmured her name, his tone somewhere between recognition and caution.
"Hello, Mr. Tendo," Kisara said with a faint smile, her voice polite but laced with venom. "Long time no see. How have you been lately?"
Kikunojo's expression hardened. "Still haven't let go of your resentment? You vengeful ghost, dragged back from hell…"
"Not resentment," Kisara interrupted, her smile widening with a cold glow in her eyes. "I'm simply protecting the best IFA under our company. The fact that it happens to be me standing here is just coincidence. Or perhaps…" her words sharpened, "…perhaps Mr. Tendo feels a guilty connection to this matter? Enough to squirm when it's brought up?"
"You dare—" Kikunojo's tone thundered with outrage, his voice commanding like steel.
"You should know this by now," Kisara cut him off. Her voice lowered, sharp as a blade. "All Tendo must die, Mr. Tendo. This isn't a warning. It's my way of life."
The temperature of the room seemed to drop.
"Kisara…" The old man narrowed his eyes, the anger in his gaze almost materializing through the screen. His very presence pressed down with the weight of his authority.
"Ms. Kisara…" Seitenshi murmured nervously, her voice betraying her unease. This wasn't how a conversation between grandfather and granddaughter should sound.
Even Rentaro felt his chest tighten. His gaze shifted between the man on the screen—his adoptive father—and the girl before him, a girl consumed by hatred. His thoughts twisted painfully.
Kikunojo Tendo had taken him in years ago. Without the man's intervention, Rentaro would've been long dead, another nameless child devoured by Gastrea. He owed his survival to him. And yet… Kisara was right. The Tendo family's sins ran deep, blood running like a curse through its veins. Kisara's hatred was not unfounded.
Still, Rentaro clenched his fists. He couldn't—he wouldn't—let Kisara destroy herself chasing vengeance against the family.
"Both of you… stop," Seitenshi's voice finally cut through, calm but firm. "President Tendo, the Holy Residence will honor its payment in full for the defeat of Hiruko Kagetane. The commission regarding the Seven Stars Relic Box will also continue as promised. So… let us end this matter here, at least for now."
Kikunojo said nothing, his cold eyes lingering on Kisara, but for the time being, both sides pulled back.
Meanwhile, the clash between Asaka Mibu and Hiruko Kohina reached its end.
Kohina lay bound in thick ropes—where Asaka had even found them was anyone's guess—her katanas scattered and useless at her side. Her face was twisted with defiance, her crimson eyes burning even as tears pricked the corners.
The Hiruko Kagetane incident, for now, had drawn to a close.
...
Later, after leaving the Ministry of Defense building, Mahiro walked silently through the evening streets, the weight of eyes following him until he reached his own home.
"Asaka, make sure no one disturbs me," he instructed as he stepped inside, the still-struggling bundle of Kohina slung over his shoulder.
"Yes, Mahiro-sama," Asaka replied firmly, her tone betraying a faint note of satisfaction at her earlier victory.
Mahiro carried the girl into his room, setting her roughly into a chair. The ropes strained as Kohina twisted violently against them, her small body writhing like a trapped beast.
Her crimson eyes locked onto Mahiro, blazing with unbroken hatred.
"This is really… troublesome," Mahiro muttered, scratching his hair with a sigh. His tone was casual, but there was a shadow of conflict in his eyes.
It wasn't as though he lacked methods to deal with her. Quite the opposite—he had plenty. But if possible, he wanted to avoid the harsher ones. A gentler way… though in this case, that might be impossible.
After all, he had killed her father. And he had done it right in front of her eyes.
Though Hiruko Kagetane had treated her more like a tool than a daughter, their bond had been real. A twisted, broken bond, but a bond nonetheless.
"…Forget it. Overthinking isn't my style," Mahiro muttered at last, his expression shifting to calm resolve.
He raised his hand, faint waves of bright psychic energy spreading outward. The air shimmered as he began weaving a bridge between his mind and hers. His intent was clear.
He would wipe her memories clean.
Erase her past, and grant her the chance to live again.
It was the method Yotsuba Shinya had once used to reforge Yotsuba Maya. Dangerous, invasive, but effective. And as one born of the Yotsuba bloodline, Mahiro had inherited that power.
"Wuwuwu!!" Kohina's muffled cries turned frantic. She didn't understand what he was about to do, but she sensed the danger instinctively. Her body thrashed against the ropes, eyes burning with fear and fury.
But her fragile will was nothing compared to Mahiro's overwhelming mental force.
Her movements slowed. Her eyelids grew heavy. Despite her struggle, despite her desperation, her consciousness slipped away under the suffocating weight of his psyche.
Mahiro's voice, calm and steady, drifted into her mind.
"Sleep. Sleep peacefully. When you wake, you'll begin anew."
"…Papa…" she whispered weakly, her last word dissolving into the silence.
And then she was still.
...
The operation was long, but it was successful. Nearly an hour later, Mahiro finally exhaled, releasing the psychic pressure. Hiruko Kohina's memories—her endless pain, her twisted upbringing, her father's blood-soaked influence—were gone.
On the bed, she lay fast asleep, breathing softly, her face at peace for the first time.
Mahiro stood by the bedside, watching her in silence.
He had glimpsed fragments of her past during the process, shards of memory etched into her spirit. What he saw made even him frown.
"You really were a sinner, Hiruko Kagetane…" Mahiro murmured bitterly.
Kohina's existence was tragedy from the start. Not born of love, but created through cruel experiments. Kagetane had kidnapped five women, using them as breeding stock to engineer his child. From her earliest years, Kohina had known nothing but the cold underground basement, trained and brainwashed as an assassin.
By the age of seven, she was forced into slaughter—pitted against her four sisters in a brutal contest of survival. One by one, they murdered each other, until only Kohina remained.
That was Kagetane's masterpiece.
Not a daughter. Not a child.
A weapon forged in madness.
A broken little girl, molded into his "perfect creation."
Mahiro exhaled again, brushing a hand over his face.
Now, perhaps, she had a chance to live differently.
*****
Legacy of the Seven Stars:
A sealed object capable of causing absolute destruction to the Tokyo Area. It can summon a Stage V Gastrea called the Zodiac Gastrea.
The object is hidden or sealed in a case that gets swallowed by the Original Gastrea during a shape‑corrosion event, when the Gastrea invaded Tokyo on April 28, 2031