"The strength of a single man is ultimately limited, Kabuto. But the strength of a group of people is an entirely different matter."
Kei looked at the silver-haired spy, who was still struggling to process the impossible offer. "You desire revenge against Danzo Shimura. But you have already admitted that taking him down alone is an impossible dream. Is that not the truth?"
Kabuto turned his head, looking through the reinforced glass at Nonō sleeping peacefully in the medical pod. He turned back and nodded, his expression hardening. "It is the truth. I cannot reach him alone."
"Then I ask you to consider joining my side," Kei offered smoothly. "While I cannot make grand promises of immediate victory tonight, I can assure you that there is more than one monster in my ranks who wishes to see Danzo bleed. We share the exact same goal. We can unite our hatred."
Kabuto hesitated, the instincts of a seasoned spy kicking in. "May I ask what 'your side' actually is? And more importantly... what price would I have to pay?"
He was overwhelmingly grateful to the blind doctor for saving their lives, but Kabuto wasn't naive. He knew there was no such thing as a free meal in the shinobi world. If Kei was offering him a shield and a blade for his revenge, the doctor had a hidden motive. Kabuto needed to know if he could afford the toll.
Kei smiled warmly. "If I had to state my price... I would say that I want you."
Kabuto instinctively took a step back, his eyes widening in alarm. "You want me?"
Kei let out a soft chuckle, waving a hand to dispel the tension. "Please, do not misunderstand. When I say I want you, I mean I require your specific talents after you wear the mask of an Avenger."
"You must understand, Kabuto, the target of your hatred commands an army. Danzo possesses wealth, influence, and personal strength that vastly overshadows yours. Even with my power and the strength of our other members, we cannot simply march into Root headquarters and execute him tomorrow. It would be suicide."
"To reach him, our organization must grow stronger. I need you to help me build that strength from the shadows. Once our foundation is absolute, your revenge will naturally follow."
Kei didn't bother using the deep, twisting psychological conditioning he had applied to Kakashi and Shisui. It was completely unnecessary. Kabuto was not chained to the village by the Will of Fire; he was a broken outcast looking for a purpose. Giving him a clear, transactional path to revenge was all it took.
Kabuto looked at the doctor seriously. "But with my limited combat skills... I cannot offer much to a war."
"The tasks I require of you do not involve fighting on the front lines," Kei clarified. He tilted his head slightly. "The Director mentioned that your mastery of medical ninjutsu is quite exceptional?"
Hearing that, Kabuto glanced down the long hallway of the subterranean laboratory, noting the pristine surgical tables and the heavy containment cells. The realization clicked into place. He understood exactly what the doctor wanted from him.
In his heart, the decision was already made. He truly had no other options left. He burned with a desperate need for revenge, and he couldn't achieve it alone. At the same time, this hidden laboratory was the only place in the world that could keep his mother safe from Danzo's assassins.
For both practical survival and his own dark ambitions, pledging his loyalty to the Avengers was the only path forward.
"I understand," Kabuto said, looking at Kei with absolute, burning determination. "I will be your hands. I will do whatever you ask of me in the dark, as long as you promise to give me my revenge."
He paused, glancing back at the medical room. "I only ask one favor in return. Please... keep my involvement hidden from the Director. I do not want her to worry about the path I am taking."
"I can respect that boundary," Kei nodded slowly. "However, I believe keeping it a secret is a futile effort. The Director is a master spy. She is not a fool; she will piece the truth together eventually."
"If I can hide my darkness from her for just a little while longer, I will," Kabuto sighed softly.
"If you insist, then we shall maintain the illusion. I will simply tell her that you have agreed to stay at the Sanatorium to work as my medical assistant," Kei smiled, pointing his cane toward the main laboratory. "Believe me, Kabuto, everything you desire will soon be within your grasp. Because from this night forward, you are no longer fighting alone."
Securing Kabuto's loyalty was a monumental victory for Kei's grand design.
While the silver-haired boy appeared unremarkable now, Kei knew the terrifying depths of his potential. In the original timeline, it was Kabuto who had flawlessly inherited Orochimaru's twisted legacy. It was Kabuto who had mastered the Reanimation Jutsu and waged a world war from the shadows. And it was Kabuto who had ultimately achieved the perfect Sage Mode, surpassing even his legendary master.
But what Kei valued most right now was the boy's unmatched genius for biological experimentation. Having a brilliant, devoted surgeon to assist with the gruesome trials would easily increase the success rate of Kei's future surgeries by at least thirty percent.
Reaching into his coat, Kei retrieved a heavily sealed scroll and tossed it to the boy. "This contains the foundational theories of human experimentation, sourced directly from Orochimaru's private archives. Begin studying it immediately."
"The Director will require a long time to heal. You can master these texts while sitting by her bedside."
"I will not let you down," Kabuto promised, clutching the dark scroll tightly. As long as it gave him the power to tear Danzo apart, he didn't care how deep into the darkness he had to sink.
With the addition of their newest member, the Sanatorium remained quietly closed to the public for the next few days.
About a week after the raid on the Blood Prison, the Zero-Tails finally awakened. And the beast that stirred within the seal was vastly different from the creature that had gone to sleep.
Its physical mass had tripled, but the true terror lay in its newly formed armor. The Zero-Tails' original body had been smooth and rubbery. While that texture granted it incredible agility, it left the beast highly vulnerable to piercing attacks.
Now, its massive, winding body was covered in thick, interlocking scales that pulsed with a deep, pitch-black glow. It radiated an ancient, suffocating weight.
Furthermore, the creature's head had mutated violently. The four soft, comical red hairs that used to flutter on its forehead had hardened and fused, transforming into jagged, terrifying black horns.
If the infant Zero-Tails had resembled a slimy, overgrown leech, the evolved beast was a monstrous, armored python with the horrific features of a dark dragon.
And matching its terrifying new appearance was an explosion of raw, suffocating power.
Feeling the vast, roaring ocean of dark chakra flooding his veins, Kei knew he had finally crossed the threshold. The strength the Zero-Tails now possessed was enough to rival a true Kage.
As the absolute master of the beast, capable of tapping into that well of power without a fraction of resistance, Kei had effectively ascended to the Kage-level himself.
He was finally free. The terrifying shadow of the Hyuga Main House could no longer touch him. If the elders tried to corner him now, he possessed the power to burn their compound to the ground.
Standing alone on the rooftop of the consultation building, the highest point in the Sanatorium, Kei let the cool night wind whip his white coat around his legs.
He looked down at his quiet, sprawling domain. The Sanatorium was peaceful tonight. But as he looked out toward the distant, sleeping estates of the great clans, a dark smile touched his lips.
It wouldn't be quiet for much longer.