douma is a girl, but when she was human, her parents wanted a boy so they made her dress like a boy and act like one to. One day, she ran into muzan who asked her to be a demon so she agreed. when douma became an uppermoon, her and daki immediately clicked, but when they all found out she died a long with her brother, douma didn't know what to feel, and he lost all his feelings since those two were friends for a very very long time.