Demon Slayer: Kimetsu no Yaiba Episode 21: Against Corps Rules

Rui, in his final moments, reflects on his frail human childhood, how Muzan Kibutsuji turned him into a demon for a stronger body, and how his parents tried to kill him, leading him to kill them instead. Realizing he severed his own family bond, he accepts he'll go to hell without them, but visions of his parents appear in the afterlife, promising to stay together forever.

Sensing Rui's grief, Tanjiro reaches out with empathy, declaring he'll keep fighting demons while respecting their human origins and inner sadness. Giyu steps on Rui's remains, warning Tanjiro against sympathizing with demons, calling Rui an ugly monster who lived for decades.

Giyu defends Nezuko from Shinobu's attack, despite her insistence that all demons are enemies per Corps rules, even offering a gentle poison death for Nezuko as Tanjiro's sister. Shinobu questions Giyu's protection of a demon, clashing briefly with him as he buys time for Tanjiro to flee with Nezuko.

Tanjiro runs desperately with his injured body, considering leaving the Corps since Nezuko will never be accepted. The girl from Final Selection—Kanao Tsuyuri—knocks Tanjiro out and pursues Nezuko, who flees like a tiny figure through the forest.

Rescuers from Shinobu's medic group administer antidote to infected slayers, lower a wrapped-up Zenitsu to safety amid the stench, and find Inosuke tied in a tree, upset he killed no one. Giyu holds Shinobu in a headlock until Kasugai crows arrive, ordering Tanjiro and Nezuko taken into custody at headquarters, while Inosuke and Zenitsu go to the Butterfly Mansion for treatment.

Tanjiro awakens surrounded by the Hashira.