Subtly warning Nonō Yakushi about the forged photographs was Kei's way of making a long-term, high-yield political investment. Having a master spy who owed him her sanity embedded within Root would prove invaluable when the time finally came to tear Danzo Shimura apart.
Returning to the Sanatorium from the orphanage, Kei plunged back into his grueling surgical routine. As the weeks bled into months, his anatomical precision grew flawless. He had mastered the delicate art of ocular vascular clearance on the black-market corpses.
Finally, after two months of relentless practice—during which Shisui successfully wired back two massive, blood-soaked bounties from the underground exchange to keep the laboratory funded—Kei was ready to operate on himself.
He had mentally simulated the surgery thousands of times. Aside from the agonizing length of the procedure, which consumed an entire night, the operation was terrifyingly smooth.
Operating purely by sensory perception, Kei successfully extracted his own eyes, painstakingly threaded the microscopic needles through his optic nerves, and flushed the hardened, necrotic blood from the vessels without damaging a single cell.
When he finally reinserted the cleaned eyes into his skull, he felt absolutely nothing. The nerves were still heavily anesthetized from the procedure.
Exhausted to his very marrow, Kei didn't bother walking back to his private quarters. He simply collapsed onto a sterile medical cot in the corner of the lab and fell into a deep, dreamless sleep.
He awoke the next morning to a sharp, burning itch directly behind his pupils.
"Did it work?" Kei murmured, his voice raspy. He immediately clamped a hand over his face to block out the harsh fluorescent lights of the laboratory, instinctively trying to soothe the burning sensation.
Having been plunged into absolute darkness for so long, the sudden, violent reintroduction of light was overwhelming. His tear ducts flared, sending hot tears streaming down his cheeks.
Ignoring the tears, Kei slowly, agonizingly peeled his eyelids open, praying to whatever dark gods existed that what he was experiencing wasn't a phantom sensory hallucination.
He had waited for this moment for so long. He had endured so much darkness that he had occasionally forgotten what color looked like.
At first, his vision was entirely blurred, a washed-out smear of gray and white. But as he forced his eyes to adjust, the shapes slowly began to sharpen. After five agonizing minutes, the blur faded into absolute, crystal clarity.
He could see the laboratory.
The physical layout of the room matched the three-dimensional map his sensory web had painted in his mind perfectly. But the feeling of seeing the gleaming steel tables and the glowing monitors with his own physical eyes was a profoundly different, intoxicating experience.
"Kei-sama? It is still early, are you not going to sleep..."
Haru pushed open the heavy vault door, carrying a tray of medical supplies. She stopped dead in her tracks, her voice trailing off as she stared at the doctor sitting on the edge of the cot.
She dropped the tray onto a nearby table, her eyes wide with shock. "Did... did the surgery succeed?"
"Yes, Haru. It succeeded," Kei whispered, fighting to suppress the overwhelming, manic thrill threatening to break his composure. "My sight has returned. How did you know?"
"Just look for yourself," Haru breathed, picking up a small, silver hand mirror from a surgical tray and passing it to him.
Kei took the mirror and stared at his own reflection for the first time in years.
He could see the physical condition of his eyes. The Byakugan had not reverted to its pure, pristine white state. The irises still appeared dull, gray, and dead.
A stranger passing him on the street wouldn't notice any difference. But Haru, who stared at his face every single day, could immediately see that the heavy, cloudy necrosis had lightened by a fraction of a shade.
"Do you want me to run a full diagnostic scan?" Haru asked, her voice trembling with excitement.
Kei nodded, handing the mirror back. Although he could see perfectly, he didn't dare flood his newly repaired optic nerves with chakra just yet. He needed to know if the tissue required a period of physical recuperation before it could handle the strain of the Byakugan.
He had run this exact diagnostic scan hundreds of times over the past few months. Haru swiftly calibrated the machine.
When the machine chimed, spitting out the medical scroll, Kei didn't wait for Haru to read the results aloud. He reached out, took the paper, and read the ink with his own two eyes.
Ocular cellular activity restored to 100% baseline. Regenerated cells have entirely consumed and replaced the necrotic tissue. Primary and secondary vascular pathways are completely clear. Blood flow normalized.
As for why his eyes still looked dead, the scanner provided the clinical answer:
Residual melanin and necrotic cellular debris have caused heavy pigment accumulation within the iris and sclera. Estimated timeline for the physical discoloration to fade: Six to twelve months.
"Congratulations, Kei-sama," Haru smiled warmly, having read the data over his shoulder.
Kei turned to look at her. It was the very first time he had actually seen his fiercely loyal assistant with his physical eyes. While his sensory web had always provided a flawless outline of her shape and posture, seeing the genuine warmth and relief on her face was a completely different experience.
"Should we test the Kekkei Genkai?" Haru asked, suddenly flushing slightly under his intense, direct stare. She quickly cleared her throat and changed the subject. "If the discoloration is merely residual pigment, the actual jutsu should function normally."
Kei nodded. He closed his eyes, took a slow, centering breath, and channeled his chakra directly into his optic nerves.
It was the first time since his reincarnation that he had ever attempted to wield the legendary power of his bloodline.
Instantly, the thick, pulsing veins bulged violently around his temples. His eyes snapped open.
His field of vision exploded. The walls of the laboratory vanished. He could see through the steel, through the earth, expanding outward in a flawless, 360-degree sphere of absolute perception.
Because he had woven heavy, sensory-blocking fuinjutsu into the Sanatorium's foundation to hide his experiments, his vision couldn't penetrate past the compound walls. But within that radius, he was a god.
And because the Caged Bird Seal was functionally dead in his brain, he experienced the true, unchained power of the Byakugan without the deliberate blind spot engineered by the Main House.
"How does it feel?" Haru asked, watching the veins pulse on his face. "Are there any issues?"
Kei held the jutsu for a full minute before cutting the chakra flow. The veins receded.
"There are no structural flaws," Kei reported, rubbing his temples. "However, because the vascular pathways have just been reconstructed, the tissue cannot handle a sustained, high-intensity chakra output yet. They will require a short period of recuperation."
It was a standard medical reality. A patient who just recovered from a catastrophic illness couldn't immediately run a marathon. The tissue needed time to adapt to the restored blood flow. He calculated the eyes would be fully combat-ready within a week.
Haru smiled, genuinely thrilled by his recovery. But a moment later, her brow furrowed with strategic concern. "Kei... this is a monumental victory, but it creates a massive political vulnerability. Once that residual pigment fades in a few months... the elders will instantly know you are cured."
Currently, the dull gray discoloration served as a perfect camouflage. But the moment his eyes reverted to their pristine, glowing white state, the illusion of the helpless, blind doctor would shatter.
If the Main House realized he had cured a necrotic disease they believed was terminal, they would drag him into a secure facility and violently interrogate him to extract the medical secrets.
Kei reached out and picked up his white cane, casually twirling it in his hand. Although he possessed perfect 360-degree vision, he had absolutely no intention of discarding the prop. It was far too valuable a disguise.
"The political vulnerability you mentioned is actually quite simple to solve, Haru."
Kei looked at his assistant, his newly restored eyes flashing with dark ambition. "As long as I can elevate my physical combat power to the Kage-level before the pigment fades... the Main House's reaction will not matter. I will simply slaughter anyone who attempts to question me."
"Kage-level?" Haru gasped softly. "Is it truly possible to cross that threshold in less than a year?"
It wasn't that she doubted Kei's brilliance, but as a Hyuga, she was intimately aware of the agonizingly high ceiling of shinobi power. It had been decades since a true Kage-level monster had been born into their clan. Currently, Clan Head Hiashi was widely considered the strongest Hyuga alive, and he was only an Elite Jonin.
The gap between an Elite Jonin and a true Kage-level powerhouse was an ocean.
"Through traditional training methods? No. It would be impossible for me to bridge that gap in a few months," Kei admitted freely. "However... if I utilize a specific external catalyst, it is entirely achievable."
The catalyst he was referring to was the Zero-Tails.
After ripping the jutsu formula from Shinnō's mind, Kei had spent months secretly cultivating and binding the dark entity to his own chakra network. That was the primary reason he had boldly challenged Might Guy to a spar—he knew he had a monster hiding in his coat if things went wrong.
During that brutal brawl with the Green Beast, Kei had confirmed that his physical baseline was now solidly in the upper tiers of Jonin. If he fully unleashed the Zero-Tails, he calculated his combat power would spike into the Elite Jonin bracket.
But that was the absolute limit of the entity's current state. To push Kei into the Kage-level, the Zero-Tails needed to evolve.
And the Zero-Tails could only evolve by gorging itself on massive, concentrated oceans of negative human emotion—terror, despair, and hatred.
The ambient anxiety he passively siphoned from his psychiatric patients was merely a drop in the bucket. To force an evolution before his eyes turned white, he needed to feed the beast a tidal wave of darkness all at once.
Unless he resorted to Shinnō's crude methodology of torturing civilians to harvest their fear—which was slow, sloppy, and highly likely to draw ANBU attention—he needed to find a pre-existing stockpile of absolute despair.
Kei's mind rapidly scanned his encyclopedic knowledge of the shinobi world's darkest artifacts. Two specific targets surfaced.
The first was the demon Mōryō, currently sealed away in the Land of Demons. The second was the legendary Box of Ultimate Bliss, an ancient artifact rumored to have been forged by the Sage of Six Paths.
Both Mōryō and the monster sealed within the Box, Satori, were entirely composed of hyper-concentrated negative emotion. If the Zero-Tails could devour either of those entities, it would instantly trigger an evolution. And as the Jinchuriki of an evolved Zero-Tails, Kei would instantly wield Kage-level destructive power.
Once he achieved that, he would never have to bow to the Hyuga elders again. He would possess the raw strength required to look Hiruzen Sarutobi and Danzo Shimura in the eye and dictate his own terms.
Weighing the logistical variables, Kei decisively locked his sights on the Box of Ultimate Bliss.
The tactical reasoning was flawless. First, the Box was currently held in the Kusagakure's maximum-security penitentiary, Hōzuki Castle. It was a stationary, heavily guarded target. Second, Mōryō was still heavily sealed by the shrine maidens, making extraction highly complicated. Third, Hōzuki Castle—known as the Blood Prison—housed thousands of the continent's most violent, despairing criminals. The ambient terror generated by the inmates alone would be an absolute feast for the Zero-Tails.
And fourth... as a maximum-security black site, the Blood Prison possessed highly advanced, brutal operational protocols for managing violently insane shinobi. Kei calculated that the Sanatorium could learn a great deal from their management structure.
It was a flawless, four-tiered tactical operation.
"Haru," Kei asked smoothly, leaning on his cane. "Are you familiar with a facility known as the Blood Prison?"
Haru thought for a moment, her brow furrowing. "The legendary black-site penitentiary in the Hidden Grass? Where the Great Nations exile their most dangerous, irredeemable criminals?"
"Precisely," Kei smiled. He shifted gears smoothly. "And what is Captain Kakashi's current operational status?"
"He has no active ANBU deployments. He has been spending his days assisting with the menial labor here at the clinic."
"Excellent. Then I will be formally requesting his elite services for an extraction mission," Kei decided. He looked at his assistant. "Furthermore, Haru, you will be accompanying us on this excursion. I want you to closely study the Blood Prison's containment protocols."
Haru nodded slowly, a dark understanding dawning in her eyes. She knew exactly why Kei wanted her to study maximum-security prison management.
After all, the Sanatorium's massive, subterranean severe-treatment ward had been fully constructed for months... and it didn't have a single patient locked inside it yet.