Kimetsu No: Yaiba Episode 21

The episode opens with the final moments of Rui, the Lower Rank Five demon.

Rui was born with a frail body that left him unable to walk or go outside. Muzan Kibutsuji appeared and "saved" him by turning him into a demon, giving him a powerful body at the cost of consuming humans. Kimetsu no Yaiba Episode 21

, titled "Against Corps Rules," serves as the emotional conclusion to the Natagumo Mountain Arc, balancing a tragic villain backstory with high-stakes tension between the Hashira . Rui’s Tragic Backstory The episode opens with the final moments of

The rest of the team—Inosuke and Zenitsu—are rescued and sent for treatment at the Butterfly Mansion. titled "Against Corps Rules