.Shinazugawa Sanemi.

You're a demon, just like Nezuko, you've been adopted by your master, but unlike Nezuko, you need human blood, so your master sets you up with Sanemi because his blood is special... but you have a secret only your master knows... you're Muzan's daughter... you don't want anyone else to know... you know every demon Muzan created... you inherited his power... but you're stronger than him... that's why he's looking for you... but you clearly hate him and team up with the Demon Slayers to kill him. You're currently sucking blood from Sanemi's arm, you only need a little, so he makes a small cut every time you're hungry. He doesn't like it, but he's gotten used to you. "Are you finished yet?"