Hiromi wasn't wrong.
At the current stage of Yoru's research into Shinigami and Hollows, the success rate of performing Hollowfication on a Shinigami was infinitesimally close to zero.
But not actually zero.
The Uchiha clan's mental state, in general, wasn't what you'd call "normal"—and Shisui Uchiha, who had awakened the Mangekyō Sharingan, and even experienced life and death to unlock the Rinnegan, was the most extreme example.
That twisted emotional depth—comparable to the extreme negative feelings locked inside the Box of Ultimate Bliss—was what gave this supposedly doomed experiment a sliver of hope.
And it was precisely that near-zero probability that allowed the experiment… to succeed.
"AAAAAAAAHHHHHH!!!"
Shisui's piercing scream tore across the sky. In that moment, he no longer looked human, but more like a humanoid Hollow.
The white substance on his face, now a mask, continued to grow and spread across his body like a bony exoskeleton. The pain that racked his body only intensified with every inch it spread, and his agonized cries became more horrific.
"Incredible… It's actually possible to graft Hollow power onto a Shinigami…"
Hiromi stared, eyes wide in disbelief, as if witnessing a miracle of the world. "Has he succeeded?"
"Not yet," Yoru replied, shaking his head. "The power of Hollows is unique. Getting a Shinigami to withstand Hollow energy is only the first step."
"To endure it, then to grasp it, and ultimately to control it... Right now, Shisui has only completed the very first step."
Being able to endure the Hollowfication meant the experiment could continue.
The Hollow and Shinigami powers would now begin their tug-of-war inside his body, fighting endlessly until one emerged victorious. That was when the experiment would truly be considered a success.
And for that, he would need Yoru's help—carefully, and slowly.
Yoru stared at Shisui's trembling, screaming body below. His eyes shimmered faintly.
"I don't want this! Yuki Yoru—I don't want Konoha's shinobi to find out what I've become! I'll cooperate, I swear!"
"What is this 'Shinigami experiment'? What are you doing to me? You're playing with souls!"
"You said only by facing death could I awaken the Rinnegan… No, it hurts… it hurts so much… I don't want to die…"
Torrents of painful memories assaulted him. Again and again. From the very beginning, he had been pushed, step by step, from Konoha's rising star—"Body Flicker" Shisui—to the broken creature he was now.
His bloodline was studied. His soul was altered. Endless experiments were performed on him. Even death-defying procedures were done without hesitation.
Over and over again, Yoru had pushed him off the cliff's edge—into a darkness without hope, without future.
His only remaining hope was Yoru's promise: that one day, he might become the "Ruler of Chakra."
Love is the source of life for the Uchiha clan.
They will give everything for what they love. For Shisui, that love was the future of the Shinobi World.
In that sense, yes—he willingly became Yoru's tool.
Of course, that didn't mean he never doubted any of it. He had questioned Yoru. But at this point… did he really have any choice?
All that anguish, all the pain he'd endured for the sake of "love" and "protection," had crystallized into a grotesque, monstrous form in his heart.
That monster looked like a composite of countless versions of himself—stitched together. Limbs upon limbs, organs upon organs. Crimson Sharingan and pale Rinnegan dotted its twisted body. But in its chest... was a gaping void.
As if it had no heart.
"Uchiha… Shisui…"
Drool dripped from the monster's jaws as it stepped toward him.
Shisui's face twisted in terror. He staggered backward in the black void—and fell.
"No… no, don't…"
"AAAAAAAAAAHHHHHHHH!!"
With wide, terrified eyes, Shisui watched the monstrosity grin—and leap toward him.
—
In the real world, the white substance around Shisui grew more rapidly, encasing his entire body.
As it enveloped him, the human form of Shisui vanished.
His limbs twisted. Skin fell away, replaced by black feathers. The mask on his face extended forward into a sharp, beaklike protrusion—eerily similar to a medieval plague doctor.
And most notably, a pair of black wings unfurled from his back.
"RRRAAAAUUUGHHH!!"
The twisted monster stood up, letting out a bone-chilling roar.
"Did he fail to endure the Hollow power…?" Hiromi asked, her voice grim. "Lord Yoru, what now?"
"Hollowfication is actually quite similar to how the Uchiha awaken the Mangekyō Sharingan," Yoru said calmly. "It all comes down to how they handle negative emotion. That's why I chose Uchiha Shisui."
"To hate their weakness… to hate this twisted world… and then turn that hatred into unyielding power—that is the Uchiha's unique 'power of love.' And to awaken it requires enduring intense suffering."
"I believe in the power of 'love' within Shisui. He has the potential to complete the Hollowfication. He can do this."
"But we can't let him go on unchecked."
Yoru turned to the air beside him. "Go meet him."
"What, fight a mindless beast?" came a cold, disinterested voice.
From thin air beside Yoru, a dark humanoid figure emerged. It didn't even look twice at the raging Hollowfied Shisui below.
"He may be mindless—but his power is real," Yoru said. "You'll benefit from seeing what a Hollowfied Shinigami can really do."
"Tch…"
The black figure snorted, then vanished from Yoru's side—appearing directly in front of the screaming, Hollowfied Shisui.
This new arrival was vaguely humanoid, with white skin, black wings, and a pair of sharp white horns sprouting from his head. He looked even more like a "person" than Shisui did.
He was called "Number One"—a name given by Yoru.
The first—and so far only—Vasto Lorde of Hueco Mundo.
In that moment, the gazes of two inhuman monsters collided.
Though he lacked reason, the Hollow instincts within Black Crow Shisui drove him forward. He lunged at Number One with terrifying speed—fast enough to rival a Shinigami's Shunpo.
But it was useless.
No matter how fast he was, he couldn't match Sonído—the Hollow flash-step that allowed travel across space itself.
Just as Black Crow Shisui's strike was about to land, Number One vanished—reappearing beside him in an instant. One razor-sharp claw slashed toward Shisui's throat.
CLANG!
The clash of metal rang out. Number One's expression turned serious.
Just as Yoru had said—Shisui might be mindless, but his stats were off the charts. Even in this partial Hollow state, his Hierro (Steel skin) was stronger than Number One's own.
The amount of spiritual pressure he was emitting was staggering.
"Power that breaks through all limits…"
Red light flickered in Number One's eyes. His previous boredom gave way to rising excitement.
"The boundary between Hollow and Shinigami… this evolution of power… Why you?! Why did Lord Yoru choose you?!"
A surge of green spiritual pressure (Reiatsu) erupted from Number One's body. Glowing energy condensed in front of him like a massive Cero.
He fired.
The blast ripped through Kirisumi Island in a titanic explosion. Smoke billowed everywhere—until Number One swept it aside, revealing Black Crow Shisui beneath a pile of rubble, completely unscathed.
This durability… this body…
The red light in Number One's eyes burned brighter.
Beneath the rubble, Black Crow Shisui rose slowly. Though devoid of consciousness, his instinct understood what had just happened.
He locked onto his target.
He was a monster driven only by the urges to kill and consume. Seeing prey before him, his instincts surged.
His spiritual pressure exploded—so violently that the entire island trembled.
"RAAAAUUUUGHHH!!"
A furious roar echoed across Jinmu Island like thunder.
Hiromi's face paled. Even Number One flinched.
"This level of amplification…"
"…Is perfectly normal," Yoru said flatly. "A Shinigami's Shikai and Bankai multiply their Reiatsu by several times. Breaking the boundary between Hollow and Shinigami only increases it further."
"Even though Shisui hasn't fully mastered his Hollow powers, just in raw Reiatsu, he's already several times stronger than before."
"Damn it…"
Number One's eyes dimmed. He sensed something.
A premonition.
His expression changed. He vanished instantly with a Sonído.
At the exact same moment, Black Crow Shisui opened his gaping beak—firing a colossal black Cero, hundreds of meters wide, straight into the sky.
It tore through the clouds like a divine spear.
If it had hit, even a Vasto Lorde like Number One would have been severely injured.
"You? You were chosen to wield this kind of power?!"
"Don't screw with me!!"
Number One roared, eyes blazing. He raised his hand. Green spiritual energy condensed, forming a high-density Cero.
BOOM!
A searing green blast shot through the air, slamming into Shisui and blanketing the world in an emerald glow. The condensed pressure warped the very air.
Gran Rey Cero.
BOOOOOOMMMM—
A thunderous explosion shattered the landscape. The ground where Shisui had stood collapsed into a massive crater.
Number One, panting from the effort, smirked.
"Stupid beast… You had power but no—"
WHUMMM.
Suddenly, every alarm in his soul went off.
He felt it.
That chilling sixth sense—the same one that had saved his life countless times in Hueco Mundo.
The feeling of death.
The wind stirred. Reiatsu surged.
In a blink, a black figure appeared behind him.
Number One's face contorted in shock. He had sensed danger—but he couldn't react in time.
SHLUNK!
A claw tore through his chest. Even his Vasto Lorde Hierro couldn't stop it.
Shisui's claw punched straight through. His other claw grabbed Number One's arm.
His beak opened wide—spiritual energy forming within it.
Cero. Point-blank.
The blast annihilated Number One's torso and soared into the ocean behind him.
A distant explosion erupted on the far shore.
Number One collapsed onto the bloodstained beach. A massive hole gaped in his chest. Blood poured from his mouth.
That one shot had destroyed all his organs.
No regeneration could save him now. He had only moments to live.
From afar, Black Crow Shisui swooped in and landed beside him.
The beak opened again—this time, not to fire.
But to devour.
A massive suction force pulled Number One in.
Yoru and Hiromi watched silently as Black Crow Shisui consumed every last trace of Number One.
"RRRAAAAUUGHH!!"
The monster shrieked and turned his gaze upward—locking eyes with Yoru.
That blood-red stare radiated madness.
"He's powerful… but completely uncontrollable," Hiromi murmured. "If Shisui's consciousness doesn't return, this thing's worth less than Number One."
"And with that kind of destructive power, if it gets loose in the Shinobi World… it would be an apocalypse."
Unbreakable Hierro. Regeneration stronger than Sage Mode. Cero blasts like Bijūdama…
To Hiromi, this thing's power exceeded even Madara Uchiha or Hashirama Senju.
"Don't worry," Yoru said. "That won't happen."
He smiled at the beast barreling toward him, raised a finger, and pointed.
"Ninety-Six Pillar Bone-Seal Suppression."
A second later, before it could even react—Black Crow Shisui was sealed.
CRASH!
A massive trident-shaped bone prison fell from the sky, pinning the Hollow monster to the battlefield.
No matter how powerful a Shinigami… he was still beneath the master of death.
"Until your consciousness returns, stay in there… Shisui-kun."
With a snap of his fingers, Yoru made the bone prison vanish.
"…Huh?"
Suddenly, he looked up at the sky.
Hiromi froze too—something fast was hurtling through the atmosphere, creating a high-pitched screech as it tore through the air.
Then a streak of light appeared.
It rapidly grew larger—brighter—descending from the sky like
a meteor.
"Is that… a person?!" Hiromi gasped. "No way… don't tell me—!"
Yoru narrowed his eyes.
The descending figure was now clearly visible—bathed in green chakra flames. Cloaked in a white robe, adorned with magatama around his neck.
Hiromi's expression tightened.
"Lord Yoru… is it them…?"
"…More or less."