The operating room was sterile. White walls. Bright lights. Equipment everywhere—monitors, IVs, instruments Sasuke couldn't identify.
Kabuto was already there, preparing. Orochimaru entered moments later.
"Last chance to back out," Orochimaru said. Not because he expected Sasuke to refuse. Just offering the option.
"I'm ready."
"Good. Take your shirt off and lie on the table."
Sasuke did. The metal was cold against his skin. Restraints locked around his wrists and ankles—not to hold him down, but to keep him from thrashing and disrupting the procedure.
"The process will take approximately six hours," Kabuto explained while inserting an IV. "We'll be implanting Hashirama cells in multiple locations—chest cavity near your heart, along your spine, and in your major chakra pathways."
"We won't use anesthesia," Orochimaru added. "You need to be conscious. Need to use your Sharingan to monitor and control the integration. Pain will be significant."
"I understand."
Kabuto injected something into the IV. "Stimulant. Keeps you conscious even if your body tries to shut down. Ready?"
Sasuke activated his Sharingan. Three tomoe spun.
"Do it."
Orochimaru's chakra scalpel cut into his chest.
Pain. Immediate and intense. Sasuke's teeth clenched but he didn't scream.
He watched with his Sharingan as Orochimaru worked. Saw the precise cuts. The careful insertion of foreign tissue. The Hashirama cells—pale, almost luminescent. They pulsed with their own chakra.
The moment they touched his tissue, the rejection started.
His cells attacked immediately. Tried to destroy the foreign material. The Hashirama cells fought back, trying to overtake his natural cells.
Sasuke felt it all. The cellular warfare happening inside him. His Sharingan perceived every detail.
"Now," Orochimaru commanded. "Control it."
Sasuke focused. Pushed his own chakra into the area. Visualized what he wanted—not destruction, not overtaking. Coexistence. Merger.
His chakra formed a bridge between Uchiha and Senju cells. Forced them to communicate instead of fight.
It worked. Barely. The rejection slowed. The cells started adapting to each other.
"Good," Kabuto monitored vitals. "Heart rate elevated but stable. Chakra levels fluctuating but within acceptable range. Continue."
Orochimaru moved to the next site. Cut along his spine. Inserted more cells.
New pain. New rejection. New battle for control.
Hours blurred together. Cut, insert, control. Cut, insert, control. Over and over.
Sasuke's consciousness wavered several times. The stimulant kept him awake but couldn't stop the exhaustion. His Sharingan felt like it was burning. His chakra reserves depleted and refilled and depleted again.
"Final insertion," Orochimaru announced.
This one was different. Larger mass of cells. Right next to his heart.
The rejection was immediate and violent. His body convulsed. The Hashirama cells tried to spread aggressively, consuming everything around them.
Sasuke's Sharingan blazed. He poured everything into control. Every technique he'd learned. Every meditation exercise. Every ounce of willpower.
The cells resisted. Pushed back. Tried to overtake him.
"Control it!" Orochimaru shouted. "Now, or you die!"
Sasuke roared. Chakra exploded from his body. His Sharingan spun so fast the tomoe blurred.
And something clicked.
The cells stopped fighting. Stopped trying to destroy each other. They just... merged. Became something new. Neither purely Uchiha nor purely Senju.
Both.
The pain faded. Sasuke gasped for air.
"Vitals stabilizing," Kabuto reported, shock evident in his voice. "Cellular integration successful. Rejection has ceased."
Orochimaru leaned over Sasuke, eyes wide with manic excitement.
"You did it," he breathed. "You actually did it."
Sasuke tried to speak but couldn't. Exhaustion hit like a wave. His eyes closed.
Darkness took him.