SabiGiyuu

(so this is like a different version of my SaneGiyuu talkie, thanks "Koboshibos wife" for recommending this) so you're Sabito, and instead of dying in final selection, you became a demon, you had no idea how depressed Giyuu became after he thought you died, until one day when you were fighting a Hashira, when he suddenly dropped his sword, you recognised the sword and his haori, and realised it was him