The deep, cold corridors of the ANBU prison echoed with the sound of Kakashi's silent footsteps. Dim Lanterns were hanging from the stone walls flickering faintly, casting long shadows as he passed cell after cell.
His destination was at the far end, the most secure chamber reserved for the most dangerous prisoners. And last time they had indeed caught a very dangerous one after he beat him up.
There, Kabuto Yakushi sat motionless, restrained in a chakra-suppressing seal formation that wrapped around the floor and the cuffs binding his wrists. His gray eyes looked up weakly as Kakashi entered, the door sliding shut with a solid thud.
Kakashi stepped forward slowly, his expression unreadable, his arms folded beneath his dark cloak. He had been thinking a lot lately of what to do with Kabuto, and the best way was to send him on his way.
"You're not here to interrogate me again, are you?" Kabuto spoke with a crooked smirk tugging at his lips.
"I've already told you everything I wanted to share." He continued
Kakashi said nothing at first. Then, without a word, he placed a small paper charm on the floor, infused it with his own chakra, and activated it with a single-handed sign.
In an instant, a gentle blue pulse filled the room, silent, but potent.
"What is-" Kabuto blinked in confusion.
Before he could finish, his body slumped, and his eyes glazed over.
Kakashi moved quickly, kneeling beside him as his fingers formed a delicate series of signs, the Mind Reflection Technique.
A rare, restricted Yamanaka jutsu he had found in the Hokage's forbidden library, he had studied and learned this jutsu, which allowed one to dive into another's subconscious and view their memories directly. Unlike the standard Mind Transfer, this was safer and didn't require switching bodies.
Kakashi's fingers touched Kabuto's temple. A moment later, his consciousness submerged into the broken, swirling maze that was Kabuto Yakushi's mind.
Years of deceit under Orochimaru. Missions taken under false identities, while he was under Danzo. Secret research. Forbidden surgeries. His inhuman transformations of other people.
But deeper still, Kakashi uncovered Kabuto's unique mastery over advanced medical chakra manipulation, techniques that rivaled Tsunade's, though twisted into something darker.
He witnessed Kabuto's Cellular Regeneration technique, a self-enhancing medical jutsu that repaired damage nearly instantly at the cost of chakra.
He also saw his hypnotic auditory genjutsu, an eerie sound-based illusion that could paralyze an opponent's nervous system mid-battle.
Kakashi memorized them all.
By the time he pulled out of the memory dive, sweat was rolling down the side of his face. Kabuto was unconscious, eyes shut, chakra suppressed to a whisper.
Kakashi stood, wiped the back of his glove across his brow, and turned away.
He left the prison wordlessly, leaving the guards staring behind him with confused glances.
Tsunade looked up from her desk as Kakashi entered the Hokage's office, closing the door behind him.
"You're back earlier than I expected," she said, brushing a stack of mission reports aside.
"I went to see Kabuto," he said bluntly. "Used a forbidden jutsu of the Yamanaka memory reading technique. I've extracted everything. His research, his unique jutsu, his knowledge about Orochimaru's networks, everything he's done. I've seen it."
"And?" Tsunade frowned as she sat up straighter.
"He's dangerous," Kakashi said simply. "Even without chakra access. He's clever and methodical. Too adaptable."
"That's putting it lightly." Tsunade exhaled through her nose.
"He's perfected regenerative medical techniques, on himself. I've absorbed them all into my own understanding," Kakashi added in a low voice.
"He also created a genjutsu based on sound. Subtle and fast. It paralyzes the target by disrupting nerve signals."
Tsunade crossed her arms with a thoughtful expression on her face.
"Could any of it be useful?" she asked, though her tone suggested she already knew the answer.
"I've already copied what was useful," Kakashi replied.
There was a long silence between them.
"What do you want to do?" Tsunade eventually sighed.
Kakashi didn't answer immediately. He stepped to the window, looking out over the village. The wind ruffled the edges of his cloak. Then, finally, he spoke.
"Keeping him alive will cost more than it's worth. He's too unstable. Too unpredictable. If he ever escapes, or worse, manipulates someone from the inside, it could bring another war." He wasn't about to let Kabuto live, he didn't want what happened in canon, to happen again.
As this is reality, many of the ninjas would be dead due to the Edo-tensei. So he decided to simply kill him.
"Then we make it official. Kabuto Yakushi, for crimes against Konoha and humanity, will be executed." Tsunade nodded grimly.
"I'll carry it out."Kakashi turned to her.
"I know, you're the only one I trust to do it cleanly," she said softly while standing up.
They exchanged a long look. No words were needed.
Back in the prison, Kakashi stood in front of the now-awakened Kabuto. The man looked up at him weakly, though there was still a glint of awareness behind his tired eyes.
Kabuto knew his time had come.
"So… this is it, huh?" Kabuto said in a dry voice.
"Execution by the Copy Ninja himself, what an honor."
"You could've been an excellent Konoha shinobi. It's a pity Danzo ruins everything he touches." Kakashi's gaze remained cold as he spoke.
"And miss all the fun? Nah." Kabuto let out a dry chuckle.
"Nono Yakushi would be very disappointed with your decisions." Kakashi looked at him and spoke.
Upon hearing what Kakashi said, Kabuto's face distorted, and he looked at Kakashi and tried to lunge at him.
Kakashi didn't flinch. He placed his hand on the seal matrix. Chakra surged around his palm, focused and precise.
"For your crimes against Konoha, for your experimentation on innocent lives, and for your manipulation of this village's enemies… You are sentenced to death."
"I wonder if Orochimaru-same will be waiting for me on the other side." Kabuto calmed down and chuckled one last time.
"He won't." Kakashi's eyes narrowed slightly.
With a single focused pulse of chakra, the seal matrix is activated in full. Kabuto's body seized for only a second before falling limp, eyes closing for the last time. No pain, no drama. He died in silence.
Kakashi remained still for a long while, his expression unreadable.
He turned and left the chamber