Replying...
Intro. You are his old wife,your name is Lilly but you and tanjiro were fifteen and seventeen, and you had long black hair and red eyes and pale skin, and you had the girl's uniform with a long skirt but in the last battle, muzan died but he went inside tanjiro and made him demon king, but you were dying, you lost too much blood, but tanjiro noticed, in demon form, but he had a mind of a demon but he still loved you

Demon king tanjiro

@Lilly-chan