After transplanting the Rinnegan into his left eye, Mizuki Ryosuke had already adapted to the profound powers it granted.
Yin Yang Release: Cellular Activation!
This was not just medical ninjutsu. It was a highly advanced blend of Yin and Yang chakra manipulation a secret technique akin to what the Sage of Six Paths once used to create life.
In his previous life, Ryosuke had read about Itachi Uchiha's Kotoamatsukami trick: Itachi had sealed Shisui's Mangekyō Sharingan into a crow and hidden it inside Naruto Uzumaki, betting on the crow to release the Impure World Reincarnation on himself with a pre-set command. That had planted the seed for Ryosuke's own inspiration.
Through Yin Release: Transcription Seal, Ryosuke etched a layer of illusion directly into the retina using a piercing needle of chakra-infused ice, ensuring the fake Rinnegan in Nagato's eye would exude the exact same pressure as the real one.
The transplanted Rinnegan, now sealed with a large portion of Ryosuke's own ocular power, emanated an eerie aura of authenticity even Black Zetsu wouldn't suspect it. Ryosuke had deliberately only implanted the left Rinnegan into himself just like Obito Uchiha, who had used a single eye to summon the Demonic Statue of the Outer Path.
"It's enough," Ryosuke murmured, looking at his handiwork. He gazed at Nagato's unconscious body, his head lowered and his eye socket newly filled with what now appeared to be a genuine Rinnegan. The chakra was just right. The ripple pattern looked perfect. Even the doujutsu's coercive force was indistinguishable.
Ryosuke didn't feel the slightest guilt. This was the shinobi world. As the saying went: "People do not kill themselves for their own sake."
Even if he had taken advantage of a wounded child, he had only done what was necessary. After all, wasn't it Nagato who'd betrayed Jiraiya the man who had saved him, taught him, and trusted him just because of a speech from Naruto Uzumaki?
Back then, when Yahiko died, Nagato killed Hanzō without hesitation. When Jiraiya died, he turned away. But when Naruto preached to him, he faltered. That wasn't conviction. That was hypocrisy.
The firelight from Ryosuke's Fire Style: Great Fireball Technique engulfed the wooden house where the secret operation had taken place.
"Let all the evidence vanish in flame," Ryosuke muttered, as the place that had witnessed a piece of the ninja world's darkest scheme collapsed into embers.
This was the very same valley where Nagato had first been abducted less than five kilometers away.
"The most dangerous place is the safest," Ryosuke recalled from a shinobi proverb. His plan an intricate dance of deception was coming together.
He turned to the preserved corpse of Uchiha Madara. The once-legendary warlord now lay dormant within an ice coffin Ryosuke had created after the man's death. His body was still biologically viable, the cells still rich with residual chakra.
From Madara's corpse, Ryosuke extracted both eyeballs. With Yang Release, he surged chakra into them to restore their cellular vitality. The Eternal Mangekyō Sharingan, without a host, had dulled significantly, but were still usable for cosmetic and illusionary purposes.
The artificial Rinnegan implanted into Nagato had a second role to maintain the illusion that nothing had changed. It had to match the spiritual signature of the real Rinnegan. With careful infusion of Yin chakra and Rinnegan residue, Ryosuke disguised it down to the smallest detail.
Next came the critical step: transplanting Madara's altered eye into Nagato's right socket making it seem like nothing had changed. This would allow the real Rinnegan to remain hidden in Ryosuke's possession while all of Akatsuki, Obito, and Black Zetsu would continue to believe Nagato was its true bearer.
This entire act was the embodiment of the tactic: "Conceal the Heavens, Cross the Sea" a feint so complete it rewrote history while history still believed itself correct.
Ryosuke looked at the now-lifeless hut, smiled faintly, and whispered:
"Next… the world itself."
The fake Rinnegan shone dimly. The ripple pattern of circles grew clearer and more majestic, mirroring the one that once belonged to the Sage of Six Paths. To the uninformed eye and even to most who were informed it was utterly real.
Ryosuke resealed his left eye. The chakra surged through his body as his real Rinnegan rested under the seal, dormant but ready.
He cast one last glance at Nagato. "You were just a piece," Ryosuke muttered. "But now, I hold the board."
And so, under the light of the burning house, the rain began to fall.
Drip… drip…
The ninja world would never know what had truly happened this night.