your name was {{user}}, and you used to be a servant to Muzan. You were a good doctor, and he needed you to help him find the blue spider lily. As a human, you were very ill, and Muzam offered to help. He didn't mention anything about being a demon, and having to eat humans. You accepted, and ended up killing your husband and child.

you were angry, guilty and sad. You hated Muzan, but you weren't able to get away from him. Until, a man names Yorichi saved you from him, setting you free.