In that moment, the first and foremost reason became clear:
Reason One: Right now, Chiyu was at his weakest.
If there were another outbreak of fighting, he simply wouldn't have the strength. Chiyu wasn't some superhuman or a late-Fourth-War godlike figure with infinite chakra and boundless stamina.
As of now, he was "only" around jōnin level—at best an elite jōnin, hardly invincible. His chakra reserves were limited; he could be hurt, he could grow weak.
Think about it: from the moment he learned what happened to Aoki and Yamakaze, to storming the Anbu prison, waging a fierce battle and killing nine Anbu shinobi, then breaking out of the prison and taking on Sarutobi Shinnosuke at the Anbu's main base—he hadn't had a moment's rest. Making it this far was practically a miracle.
Reason Two: Uchiha Fugaku was still in Anbu custody.
Without their clan head, the Uchiha were leaderless. Uchiha Yashiro and Uchiha Yakumi alone couldn't possibly hold the situation together—a head-on clash would be suicide.
After all, on the other side stood Sarutobi Hiruzen, Hatake Kakashi, code-named "Baku," "Sunny," "Sparrow," "Horn," and numerous other Anbu elites—not to mention Shimura Danzō and the Root lurking, watching for an opening.
And the Uchiha's top fighter, Uchiha Shisui, might turn on them at any moment.
Under such circumstances, the Uchiha launching a rash assault would be destroying themselves.
Reason Three: Everything Chiyu did was in the name of justice, and that would never change.
Call him stubborn, call him foolish—he would still hold to it. In his eyes, having killed Sarutobi Shinnosuke while he was suspended from duty, being locked up during the investigation was an acceptable protocol.
Reason Four (critical): He possessed an absolute safeguard.
Under the escort of Hatake Kakashi, "Baku," and a dozen elite Anbu, Chiyu was finally brought to the Anbu prison entrance. A group of people had already gathered there, eyes burning with hatred, longing to rip him to shreds. Even Kakashi couldn't help sighing inwardly at the sight. For Chiyu to step willingly into the hands of those who harbored such deep hatred—his fate might be worse than death.
Though Kakashi was Anbu, his feelings toward the Uchiha were complicated. The comrade most important to him had been an Uchiha named Obito; his own left eye was a gift from that friend's final moments. In the depths of his soul, Kakashi felt some debt toward the Uchiha. This was partly why Hiruzen didn't want him too involved in Uchiha affairs.
"Baku" spoke in a low voice: "Kenpei, this man is yours."
That Anbu jailer Kenpei gave a curt nod. Chiyu knew him by name—Aburame Kenpei—an outstanding member of the Anbu. He approached Chiyu, along with seven or eight other elite Anbu, all activating a technique that could seal all chakra and jutsu:
"Seal Technique: Method of Sealing!"
"Four Limbs Weighting Seal!"
Chiyu's brow twitched. He knew these were high-grade sealing arts from the Uzumaki clan, Konoha's allies. The "Method of Sealing" blocked all chakra circulation so a ninja couldn't use any ninjutsu or genjutsu, while the Four Limbs Weighting Seal bound physical strength as well—effectively nullifying taijutsu. A double-layer seal would strip any ninja of combat power.
The very instant those Anbu combined efforts to activate both seals, Chiyu quietly employed his Mangekyō Sharingan's eye technique:
Kuyebiko—his left-eye power!
Earlier, when the Anbu unsealed Fugaku, Chiyu had used Kuyebiko to unravel the method behind it. Now, with what little chakra and ocular power he had left, he carefully wove a tiny gap into his own seal—enough that he could free himself at any moment, and no one realized a thing.
This was the terror and might of Kuyebiko. Its ultimate insight uncovered every flaw, enabling him to exploit those hidden vulnerabilities. In the face of Chiyu's left eye, no ninjutsu was truly impenetrable.
The double-layer seal complete, all the Anbu finally breathed easy. Then their eyes filled with triumphant malice. Chiyu, of course, saw through them right away.
Aburame Kenpei said coldly, "Kakashi, Baku, leave him to me…
"I'll make sure he's well watched."
Elephant smirked darkly. Kakashi simply shook his head slightly, watching Chiyu get shoved rudely through the gates.
Kakashi couldn't help asking, "Uchiha Chiyu… why did you designate me to investigate this?"
Turning his head a bit, Chiyu offered a rare hint of a smile.
"Out of all the Anbu, you still seem at least somewhat human."
Kakashi's heart lurched. The other Anbu bristled in anger.
One of them shoved Chiyu deeper into the dark prison. Kakashi stared at the door closing behind him, pondering that remark. Elephant gave him a meaningful glance.
"Remember, you're a clever man. You know this is a hot potato—slip once, and you're done for. Most importantly…" Baku paused, "Chiyu's motives don't matter, and neither do yours.
"What matters is… how will the Hokage interpret them?"
Kakashi's mind tightened, grasping Baku's meaning.
"I'm only telling you this because of the White Fang's memory. Also because you really are one of Konoha's rare talents. Take it or leave it," Baku murmured. With that, he headed off. He served as Hiruzen's personal guard Anbu, so although he and Kakashi were colleagues, their duties differed.
Kakashi watched him go, then sighed heavily. He looked skyward, feeling a pang of uncertainty. Unsure how to proceed, his feet led him toward the Memorial Stone—seeking a talk with old friends long gone.
Chiyu was shoved deeper into the prison, the gate slamming shut behind him.
The hidden chuckles of those Anbu were cold and cruel.
"Uchiha Chiyu, we've got quite a welcome prepared for you…"
But Chiyu had already sensed it. In the gloom, shadows reeking of rot and malevolence began closing in from all sides.
He only curved his lips in a faint smile.
This was his final reason for accepting imprisonment. To carry out justice and wipe out evil, where better than the Anbu's darkest cell?
Putting him—like a lion—into a cage of rabbits?
They believed they'd snared a captive, but in truth…
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