Disclaimer: This chapter contains emotional and thematic content centered on trauma recovery, moral conflict, and human empathy within a dystopian setting. All characters under 18 are depicted non-sexually and within canon-accurate emotional contexts. Any affection or attachment is presented from a child's emotional perspective, not romantic or sexual. This work does not contain or endorse explicit sexual content involving minors. Reader discretion is advised for violence and mature themes.
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What should I do?
The answer that screamed in the Seitenshi's mind was as brutal as it was simple: Loyalty! To follow behind him without question, become his unwavering supporter, and watch as he dragged the corrupt and the cruel from their gilded thrones to face their bloody retribution!
There was no other choice!!
…Of course, the Seitenshi would never actually do that. Such a path of carnage was antithetical to her very soul. However, from that fateful day on the overpass, she never sought Mahiro out again. Her visits to Arcadia ceased, though she quietly ensured a steady, discreet stream of supplies reached the district.
More importantly, her governing style underwent a profound and subtle shift. The gentle, almost naive idealism was being tempered in a forge of harsh reality. She began to forcefully push back against dissent, her methods growing noticeably tougher and more decisive.
Her first move was to dismiss the corrupt police inspector, Kouzuma, and his son, leveraging a small but undeniable piece of evidence to have them imprisoned. Immediately after, she began forcefully advocating for the long-stalled 'Gastrea New Law,' her attitude so unyieldingly firm that even her chief assistant, the venerable Kikunojo Tendo, could no longer remain a passive observer.
(No named police inspector in canon)
While a part of him was pleased to see the girl he had watched grow up finally hardening her resolve, he was deeply dissatisfied with the direction of that resolve. Disregarding his own position and decorum, he confronted the Seitenshi in several heated arguments.
Unfortunately for him, a new, chilling resolve had taken root in her heart.
"This world… has long since rotted into a cesspit. Polishing a single stone on the shore will not change the tide…"
...
During this period, an unusual tranquility settled over Mahiro's life. Not only had the Seitenshi fallen silent, but even the fiery Tendo Kisara had ceased her provocations. Seizing this moment of calm, Yotsuba Mahiro began to boldly and openly pursue his own ambitions.
First, he formally transferred Aihara Enju to live permanently in Arcadia. Then, he initiated a sweeping operation, systematically gathering every scattered, hidden Cursed Child throughout the Tokyo Area and bringing them under Arcadia's protection. Even the shrewd Shiba Miori, while assisting with the district's infrastructure construction, quietly began moving several of her business ventures into the territory.
As Arcadia's scope rapidly expanded, eventually occupying the entire Thirty-ninth District, he stopped hiding this nascent nation of Initiators. He pulled back the curtain, exposing its existence fully to the watching world.
This, of course, drew immediate attention. Representatives from the IISO visited him on multiple occasions, intending to "discuss" the "distribution and management" of the Cursed Children. But each time, they were sent away empty-handed. Their leverage was gone; neither the lure of official Promoter rankings nor the threat of withholding inhibitors had any effect on him anymore.
All of this newfound independence was thanks to one person: Doctor Sumire Muroto.
...
The culmination of her work arrived on the day Sumire Muroto finally moved her entire laboratory operation from its dank basement to a state-of-the-art facility within Arcadia itself.
Lined up on a sterile table were rows of small syringes. Two distinct serums had been successfully developed: an enhanced serum derived from the cells of the Stage Five Zodiac Gastrea, Scorpio, and a revolutionary inhibitor serum capable of permanently halting the increase of the Gastrea virus corrosion rate.
"So, this is it?" Mahiro picked up one of the syringes, his gaze intense as he studied the blood-red liquid within.
"That's right," Sumire Muroto declared, stretching her arms above her head with a heavy, satisfied sigh. The motion was unashamedly languid, accentuating the graceful curves of her body beneath her white lab coat and offering a tantalizing glimpse of her fair waist and a playful navel. After a long moment, she finally lowered her arms. "I've named it the AGV experimental drug. Its effects will completely achieve the results you desire."
Of course, he wouldn't just take her word for it. Activating his unique analytical sight, he simulated the serum's interaction with a biological system. The results that flashed before his eyes confirmed her claims. It could not only cause a person's regenerative abilities to skyrocket and comprehensively enhance their physical prowess but also purge all known diseases. This exaggerated effect could even grant temporary immunity to the disruptive magnetic field radiation emitted by Varanium.
But the drawback was still glaringly obvious. A risk of Gastrea transformation still existed—a huge, inherent flaw that could not be entirely overcome.
"A 98.74% success rate… That's already incredibly impressive, Doctor Sumire. This is enough to go down in history," Mahiro praised, his tone one of genuine respect.
"Since you know that, you'll have to properly enshrine me from now on, you cheeky brat," Sumire Muroto retorted, leaning back against the lab table and crossing her legs, idly swinging one foot. The slender tip of her high-heeled shoe traced lazy, alluring arcs in the air. "Well, I suppose you contributed your fair share, too."
Hearing this, Mahiro looked up curiously, meeting the doctor's teasing gaze.
"It's the Scorpio blood sample you brought back," she explained, her tone shifting to one of clinical calm. "It contained the most primitive, initial Zodiac Gastrea sample. By decoding its genetic fragments and cross-referencing it with the blood of the Scorpio girl you retrieved, I was able to compare her DNA blueprint and chromosome count against other Initiators. The key was isolating the regulatory gene sequences that govern the viral expression without triggering the catastrophic morphological cascade…"
It was pure gibberish to him. Sumire Muroto launched into a fluent, rapid-fire monologue filled with dense professional terminology, the kind that would baffle a liberal arts student and give a science major a migraine. She noticed his glazed expression but didn't stop, a subtle, playful smirk on her lips as if she were enjoying his confusion.
Only at the very end did her tone shift again, the scientific lecture concluding as she got to her real point. "...That's the gist of it. It's fine if you don't understand. Just remember the part about my reward, boy."
The last piece of the game was on the board, and the dagger lay in plain sight. He knew he couldn't avoid it, and since he had no intention of backing down, he didn't pretend otherwise.
"I'll test the goods first," he said directly, his voice firm. "Then we can talk about your reward."
Without another word, and under Sumire Muroto's watchful, slightly surprised eyes, he picked up a syringe, pressed it against his arm, and injected the crimson liquid directly into his vein.
"You're quite the bold one, boy," she remarked, genuinely taken aback by his decisiveness.
Mahiro managed a faint, strained smile. "What does it matter? At worst, I'll turn into a Gastrea and eat you in one bite."
"That wouldn't be so bad either~" she purred, her voice dripping with a dangerous allure. "A new type of love suicide, perhaps?"
But before Sumire Muroto could finish her teasing words, the smile on Yotsuba Mahiro's face froze solid. His expression contorted, twisting into a mask of pure, unadulterated agony.
Pain!
An agony that drilled into his very bones, that scoured his soul! It was a white-hot, all-consuming fire that eclipsed even the metaphysical torment of having his information body's history overwritten during a trace!
THUMP-THUMP-THUMP!
His heart hammered against his ribcage like a wild beast trying to break free, each beat a deafening, visceral drum solo echoing within the chamber of his chest. As the modified serum surged through his arteries, he could literally hear the sound of roaring tidal waves crashing in his ears. His limbs, his entire body, felt like it was being inflated from the inside, muscles and sinews stretching to their absolute limit. And his brain… it felt like it was being physically torn in two, neurons screaming under an overload they were never meant to bear!
It was as if he had been doused in gasoline and set ablaze; his entire being, every single cell, was screaming in incandescent fire. The drug had no gentleness, no finesse—it was pure, unadulterated, primal ferocity.
If he could form a coherent thought, if he could speak, he would have roared—'Is this fcking thing meant for humans?! Are you trying to kill your test subject, you mad scientist?!'*
But he didn't notice that his irises were now stained with a layer of brilliant, vibrant crimson, a shade even more intense and piercing than the characteristic red eyes of the Cursed Children.
(Achieved Mangekyo Sharingan)
Yet, as violently as it had arrived, the pain vanished. The ten-second eternity of torment ended as abruptly as it began, replaced by a wave of profound relief and electrifying pleasure. He slumped back into the chair, drenched in sweat as if he had just been pulled from the ocean, his chest heaving.
"Hah… that was deadly…." he gasped, his voice raw.
But the effect was undeniable. A raw, untamed power coursed through him, as if he had shattered a fundamental barrier and stepped into a realm beyond human limits. His mind was sharper, clearer than ever before, producing an almost euphoric sense of exhilaration.
"It seems the experiment was a success… What a shame," a playful, familiar voice cut through his recovery. "It looks like we won't be able to commit that love suicide after all."
He heard a soft rustling sound. Mahiro instinctively opened his eyes—when had he closed them?—and saw that Sumire Muroto had, at some point, glided to stand directly before him. Her white lab coat lay discarded on the floor like a shed skin.
Now, she was clad only in a sheer, dark purple blouse, transparent enough to reveal the silhouette and color of what was beneath, and a form-fitting pencil skirt that showcased the elegant curve of her hips and the beauty of her legs, sheathed in sheer black stockings. She took a final, graceful step in her black high heels, closing the last bit of distance.
However, before he could fully process the sudden shift in atmosphere, Sumire Muroto deliberately let her balance falter, tumbling gracefully into his lap and settling there, facing him.
"Now," she whispered, her breath hot against his ear, "it's time for my reward, boy."
But the next second, she involuntarily took a sharp, shaky breath.
"Gulp…."
"Gulp? Doctor, what was that sound?" Mahiro asked, his strength rapidly returning to its peak—and then surpassing it. The dynamic shifted instantly, the power balance tilting from his passive recovery to his active control.
"But Doctor Sumire, are you the queen of the impatience kingdom?" he teased, a slow smirk spreading across his face. "Can't you at least let me take a shower first? I'm drenched."
"Hehe… What, what does it matter?" Sumire Muroto panted, her arms already tightly wrapped around his neck, her composure beginning to fray at the edges. "Rather… since you're so… skilled… just how many women have preceded me, I wonder?"
"Haha, Doctor, at a time like this, do you really care about that?" he chuckled, his hands settling on her waist. "That doesn't sound like you."
"Hah… After all, I'm also a woman, Mahiro-kun," she breathed out, her voice laced with a rare vulnerability. "But you're right… this really isn't like me at all… Ugh!" Her words cut off into a choked gasp as Mahiro shifted beneath her.
He moved from his reclining position in the chair to sitting fully upright. The sudden change in angle caused Sumire Muroto to slide downward with a soft gasp, only for Yotsuba Mahiro to promptly wrap a firm arm around her waist and pull her back up, their bodies colliding with a soft, impactful thud that forced another deep, shuddering breath from her lungs.
Sumire Muroto: "..."
She could only gaze at him with half-lidded, profoundly resentful eyes, her usual lazy dominance utterly shattered.
He hadn't expected this typically indolent genius to have such a charming and alluringly vulnerable side. It was a stark contrast that, for a fleeting moment, made him think of his own formidable mother, Yotsuba Maya. What was she truly like underneath all that power? The thought was immediately dismissed as both terrifying and unimaginable.
Knock. Knock. Knock.
Just then, the electrically charged intimacy was shattered by a sound as crisp and intrusive as a gunshot. A calm, firm, yet impeccably polite knocking echoed from the laboratory door.
Sumire Muroto's body instantly stiffened in his arms, every muscle tensing. Her slender brows furrowed in a mix of frustration and panic. One of the world's most brilliant minds went completely, utterly blank, occupied by a single, screaming thought:
Who is it?! And at this hour?!
She had specifically chosen this late time, long after bedtime, to ensure they wouldn't be disturbed.
"Doctor? It's me, Tina." The voice from the other side of the door was soft and polite. "I'm sorry to disturb your rest so late. Is Mahiro-sama with you?"
Tina?
Sumire Muroto's eyes snapped back to Mahiro's, a silent, accusatory question burning in them: Why is that girl looking for you at this hour?
"Ara ara," she whispered, her voice a husky, teasing murmur directly into his ear. "Are Kisara and the Seitenshi not enough for you? Are you now extending your devilish claws to those innocent children, you loli-con gentleman?"
But the very next second, her body trembled violently, and she had to use every ounce of her willpower to swallow the gasp that fought its way up her throat.
Knock. Knock. Knock!
Perhaps due to the prolonged silence, the knocking came again, a little more insistent this time.
"Doctor Sumire? Are you already asleep?"
If they just remained quiet, the girl outside would likely assume she was asleep and leave. But with Sumire Muroto's mischievous and prideful nature, how could she simply be that obedient? Forcing her voice to remain steady despite its obvious tremor, she called out towards the door:
"….N-Not yet! What is it?!"
"Oh, it's like this, Doctor. I have something I wish to discuss with Mahiro-sama, but he's not in his room. Is he perhaps with you?"
"Hehe, no, he's not~" she managed, straining to keep her tone light and dismissive. "That perverted brat must be enjoying himself in some other woman's arms right now. You should try looking at President Kisara's place. Oh, and be careful not to be attacked by that person when walking at night… Gulp!"
"Doctor? What's wrong?" Tina's concerned voice filtered through the door.
"….It's nothing!" Sumire Muroto bit out, her words slightly strained. "I just… bumped into the corner of the table!"
Even as she said this, the hands she had wrapped around his neck tightened with enough force to genuinely threaten his airflow.
"Tina, if there's nothing else… I'm going to rest now," she managed to push out.
"All right. Please be more careful, Doctor Sumire. I'll take my leave now."
After Tina's polite response came from the other side of the door, the sound of her soft footsteps gradually faded away down the hall.
"Hehe… Quite the perverted onee-san, aren't you, Doctor Sumire?" Yotsuba Mahiro managed a strained, fake smile as he looked at the woman currently pinning him against the lab table.
"Then what are you going to do about it~?"
At this moment, Sumire Muroto was like a different person entirely, as if a hidden switch had been flipped. The usual decadent, alluring beauty had transformed into something far more primal and predatory—a veritable succubus unleashed. Her long, brown wavy hair obscured half of her delicate face, which was adorned with a faint, dangerously seductive smile. She looked even more intoxicatingly alluring than before.
...
The "overtime" research session in the laboratory continued long into the night, the sterile white lights illuminating their private world.
"Are you satisfied now?" Mahiro asked, his voice a low rumble.
"Heh heh… Not bad at all. I'm very satisfied, boy~"
Despite her words, Sumire Muroto—hailed as one of the "Four Sages," one of the world's most brilliant minds, frantically sought after by countless nations—was now sprawled haphazardly and bonelessly across the laboratory sofa. Her legs trembled uncontrollably, a testament to the exhaustive "experimentation."
But even in her thoroughly spent state, a flicker of the mad scientist remained. With a trembling hand, she picked up a sterile test tube, carefully collected a specific sample, sealed it with practiced efficiency, and placed it in a refrigerated unit. Only then did she stagger towards the bathroom, moving on unsteady legs.
She didn't forget to glance back over her shoulder, her voice a husky, playful whisper. "Care to join me for round two?"
Yotsuba Mahiro: "..."
This woman… Despite having preserved her "purity" for so long, the psychological pressure had clearly warped her in its own unique way. Her identity as a genius and a mad scientist was utterly undeniable.
...
The next morning, surrounded by a chattering flock of Cursed Children, Mahiro arrived at the state-of-the-art training ground recently constructed by Shiba Heavy Industries within Arcadia.
His designated opponent was Aihara Enju, her twin pigtails bouncing like eager rabbit ears.
"Mahiro-nii! This maid is about to begin~!" she announced, striking a playful fighting pose.
"Come on whenever you're ready," he replied, settling into a relaxed stance.
His original plan was simply to test the limits of his newly enhanced physicality, but he hadn't expected Enju to so eagerly volunteer for a sparring match. Perhaps, with Tendo Kisara accepting fewer agency requests lately and a powerful new fighter like Tina joining their ranks, Enju was feeling a sense of crisis. Did she feel an urgent need to prove her own worth and secure her place?
Mahiro couldn't help but speculate.
However, all thoughts vanished as Enju unleashed her power. Her legs, empowered by her rabbit factor, bent like powerful springs before she pushed off the ground, instantly bursting forth with incredible jumping force and lunging forward like a released arrow.
'She's really fast, this kid.'
Yotsuba Mahiro evaluated coolly in his mind. This raw speed surpassed even that of Chiba Erika and Watanabe Mari when they used their Acceleration-type Magic Sequences. An ordinary person trying to track her with the naked eye would see nothing but a blur of afterimages.
But.
He was no ordinary person!
Whoosh!
"Eh…?"
Enju's eyes widened slightly, a look of pure confusion flashing in her crimson pupils. She completely failed to comprehend what had just happened, only knowing that her perfectly aimed side kick had been effortlessly, inexplicably dodged by a minuscule shift of his body.
"Heiya!"
The moment her feet touched the ground, Enju launched another assault. Her low-to-high kick, swift and sharp, somehow grazed past Mahiro's form without making contact. As if her movements were being broadcast to him in advance, every subsequent punch, kick, and lunge was perfectly evaded. It was as if he could see through every single one of her attacks.
But the baffling part was that her attacks were inherently haphazard, a chaotic flurry with no discernible pattern or rhythm.
"...Mahiro-san is amazing. He can keep up with Aihara Enju's movements," murmured Senju Kayo, who had put down her work to watch the match. Though her voice was soft with awe, it also carried a sense of inevitability, as if she expected nothing less from him.
"No."
Tina, having just finished her morning sniper drills, gently shook her golden bob. Her sharp eyes analyzed the scene with a Promoter's precision. "Mahiro-nii is playing with Enju-chan. He's not being serious at all."
To be honest, Tina was truly shocked. She knew Enju's combat prowess was considerable; her rank should be far above 100,000, easily within the top 100. But the speed she was demonstrating now meant that in close combat, Tina herself would be at a severe disadvantage and would need to rely on traps and tactical tricks to win.
And then there was Mahiro. Aside from his previously displayed, unanalyzable magical abilities, his current physical speed and reflexes had clearly surpassed Enju's.
Her sisters, the other NEXT series initiates, shared the same sentiment. While Enju herself was impressively strong, they were shocked to realize—
Compared to the last time he had so easily captured them, this man seemed to have grown even more powerful.
This was especially true for Rita Sosberry, IP Rank 21, the one known as "Pluto." Her experience had been… particularly memorable. Even now, a faint, phantom ache resonated from her backside, and her gluteal muscles would twitch unnaturally at the memory.
Watching him now, so effortlessly toying with a speed-type Initator, she was once again overwhelmed by the fear of being utterly dominated by Yotsuba Mahiro. A full-body shudder wracked her small frame.
'I can't resist this demon at all... Am I just destined to be suppressed by this man for the rest of my life?'
Meanwhile, the match on the field was reaching its conclusion.
"Ha ya!"
With a final, spirited cry, Enju unleashed her trump card—a powerful, whistling high kick, the force of it cutting through the air like a miniature dragon. The angle of the attack, however, was rather… thought-provoking.
"I say, Enju," Mahiro sighed, easily catching the kick and firmly grasping her slender ankle, halting her momentum completely. "If you choose to wear a skirt to a spar, you really shouldn't rely on high kicks. Otherwise, your panties are on full display for everyone to see."
Enju, hearing his blunt assessment, froze mid-stance. Her fair face visibly reddened at a rapid, impressive pace, and she instinctively used her free hand to press down on the hem of her fluttering skirt. But in her current, precariously balanced posture, the attempt was utterly futile.
Taking advantage of her flustered distraction, Yotsuba Mahiro suddenly spun on the spot, using her captured leg as a pivot to swing her in a wide circle before releasing her with a controlled, gentle force. The throw sent Enju flipping gracefully through the air, but it completely broke her offensive rhythm, leaving her unable to launch another immediate attack.
"The match is decided. That's enough," declared Asaka, acting as the referee, her voice calm and final as she ruled Enju the loser.
Through this spar, Yotsuba Mahiro had gained a clear understanding of the enhancements granted by the AGV serum. Firstly, his raw physical strength had already surpassed that of the Initators within Arcadia who possessed ant-factors, a type specialized for pure power.
As for speed, the results were undeniable; he had easily outpaced Enju, the fastest among them. Furthermore, his brain development—his cognitive and processing speed—had received a comprehensive and significant boost. At the very least, performing a feat like pulling a meteorite from Earth's orbit would no longer leave him so utterly drained.
And then there was the progress on his analysis of the Philosopher's Stone conversion ritual. The progress bar, which had been stalled at 32%, had now skyrocketed to 60% in one go. Previously, his matter conversion was limited to metallic elements, like transmuting base materials into gold or rare metals like holmium.
But now… the scope had expanded dramatically. He could, through his own power and understanding, perfectly recreate the AGV serum developed by Sumire Muroto, as well as the potent inhibitor that perfectly suppressed the Zodiac Gastrea virus.
It was a somewhat terrifying realization. He was becoming a living, breathing Philosopher's Stone, wasn't he? And this was only at just over half of the total analysis progress. If it ever reached 100%... what heights could it achieve? Creation of matter from nothing? The genesis of a new world? Or, like a certain green-haired character in A Certain Magical Index, could he make anything he wished come true?
Yotsuba Mahiro no longer dared to imagine the possibilities. The path ahead was both exhilarating and terrifying.