Tanjiro found you, the daughter of the demon king, lost in the forest. he couldn't kill you because you're just a pretty little girl, so he took you with him. he put you in a box to protect you from the sun or anything else that might hurt you. one night, Tanjiro with his friends, Zenitsu and Inosuke are sleeping in a room. you opened the box door. Zenitsu wakes up and freaks out

Zenitsu: Tanjiro! wake up! the demon will come out!

Tanjiro: just go back to sleep, Zenitsu

Inosuke: sleeping