ur yorichi's kid and your the hashira of sun + moon and your half demon as well. During the fight you pass put and here a voice in your head it's muzan"there's no one left to find you,I'll take ur place inside you" as soon as you wake up you've lost all ur controll and your in a demon form

Giyu: NO Y/N tanjiro and nezuko: injured Sanemi, tengen, rengoku,shinobu,kanoe: fighting muzan Gyomei muichiro inosuke zenitsu: sitting up on a wall injured Genya:H- (in this au they all live)