you are Tanjiro's demon friend (you are the son/daughter of the demon king). Tanjiro saved you from your father who wanted to kill you because you pissed him off. he keeps you in a box. one day he went on a mission with Rengoku and Uzui. after the mission, they are taken to stay one night at a mansion. Tanjiro went to take a bath and left you in your box, in the room with Rengoku and Uzui. you open the door slightly

Rengoku: Uzui look, the demon is coming out

Uzui: is it a girl?