The black chains, symbolizing Ren's life, meant Yoriichi could end it at any moment.
Ren had left the choice to him.
But in that critical moment, Yoriichi hesitated.
In that second of hesitation, Ren became a blur, charging toward the Water Hashira.
For Yoriichi, those few minutes stretched like centuries, each second an agonizing torment.
Time seemed to freeze, as if congealed.
A mere second felt like an eternity.
Yoriichi stared at the black chains binding him, his expression hollow, drained of strength and resolve.
As a swordsman, he had devoted his life to the blood-soaked path of slaying demons.
Yet now, he stood motionless, watching a demon wreak havoc.
Deep within, Yoriichi plunged into self-doubt.
The one who became a demon was his own disciple, taught by his hand!
Faced with this tragedy, he, the master, failed to intervene, instead standing by as his disciple killed mercilessly.
The Water Hashira's anguished screams pierced Yoriichi's ears like a blade, echoing relentlessly in his mind.
As Yoriichi wrestled with his turmoil, the screams ceased, and a fleeting silence settled over the world.
"Master…" A familiar yet alien voice broke through his thoughts.
Yoriichi opened his eyes slowly. Ren approached, holding the Water Hashira's head.
Despite bracing himself, Yoriichi's face betrayed shock, his hand instinctively reaching for his Nichirin Blade.
"Oh, sorry, Master." Ren noticed Yoriichi's reaction, his movements flustered.
Like a child caught misbehaving, he hurriedly tossed the head aside, scratched his head sheepishly, and offered a shy smile. "These years, I've grown used to treating enemies this way. I lost control for a moment. Please forgive me."
The black chains still bound Yoriichi, meaning he could still end Ren's life at any time.
Ren sat beneath a tree, closed his eyes, and waited. After a few seconds of silence, he opened them, puzzled.
"You're not going to kill me?"
"Let this be the end, Ren," Yoriichi said, closing his eyes in pain. "From now on, stay by my side. Let me be your restraint."
"I'm sorry, Master, I can't agree," Ren said softly. "Fear will silence all rumors. Our feud with the Demon Slayer Corps is settled. Next, I'll go to the Sound Hashira's home and erase all his kin from this world."
Having just skirted death, Ren made another reckless vow.
Yoriichi frowned. "Ren, I said, let this end!"
"Master, I promise, after this final act, it will end," Ren said. "Don't tell me 'their families are innocent.' From the moment they harmed Chitoshi, anything I do to them is justified. Please indulge me one last time."
Yoriichi opened his mouth, then paused. "And if I stop you?"
"You can kill me, but you can't stop me," Ren replied. "I swear, after this, I'll return to your side and accept your judgment."
"Ren…" Yoriichi's face was heavy with sorrow. "I know Chitoshi's death struck you deeply. My heart aches too. But must it be this way? Is there no better solution?"
"Master, it's too late for that," Ren said. "Chitoshi is dead. I no longer care about right or wrong. The only way to resolve this is to bring him back.
From the moment he died, I could never turn back."
"Muzan!" Yoriichi growled, teeth clenched.
In that moment, his hatred for Muzan Kibutsuji peaked.
He loathed Muzan, but he loathed himself more.
He cursed his failure to kill Muzan. Had he succeeded, none of this would have happened.
Why was he so useless?
Hadn't the heavens granted him immense power to destroy Muzan and prevent his havoc?
Yet what had he done?
He'd had the chance to kill him but failed, leading to this cascade of tragedies.
All because of him.
"You don't need to blame yourself or grieve for others' choices," Ren said calmly. "This path was my choice, not your fault. You don't have to bear every burden."
"Ren, you're a good child. As I've said, I took you as my disciple not for your talent but for your heart, radiant as the sun," Yoriichi said softly. "I see you haven't fully fallen, even as a demon. So promise me, don't let a moment's impulse lead to lifelong regret, alright?"
Yoriichi looked at Ren, his blood-red hair stark, and sighed. "Come with me. If you refuse, I'll break your legs and drag you."
"Thank you, Master, for giving me this time," Ren said, rising. "My words stand. After killing the Sound Hashira's family, I'll find you."
With that, his body dissolved into countless crows, scattering into the sky.
"Wait, Ren, what are you doing!" Yoriichi moved to stop him, but despite his speed, a few crows escaped.
"Master." Ren's voice echoed in Yoriichi's ear.
"Please live well."
Yoriichi fell silent, staring in the direction Ren vanished.
Ren's voice lingered faintly. "If you die, no matter how, I'll unleash a massacre. So, to save others, be the lock that binds me."
Yoriichi didn't know how Ren saw through him. Perhaps he knew his disciple too well, just as Ren knew him.
His disciple's fall had sparked thoughts of seppuku to atone, but Ren's words dispelled them.
Yet, as a master, he should have purged his demonic disciple. Instead, he let him go!
Yoriichi, you're as much a failure as ever.
"Ren, heed my words. If I find you causing chaos, no matter where you are, I'll kill you myself," Yoriichi said, gripping his Nichirin Blade, his resolve unshakable.
No one doubted his words, least of all Ren.
"I understand, Master."
Yoriichi turned, raising a hand in a wave, mirroring their parting years ago.
Ren, seeing it from afar, smiled.
He was transported back to that afternoon—Chitoshi at home, preparing sushi, awaiting his and Yoriichi's return from missions. They'd set out separately, those days so perfect, so truly perfect.