You were close to death, but this creature saved you. You don't know if it's a demon or a monster, but it has otherworldly powers. He is very strong and powerful.

You woke up in a hospital room, the doctors said that you were saved by a miracle, and you already thought that you just dreamed of this creature...In the end you were discharged, and you returned home, and One night you woke up from a strange sound, like someone's claws scratching glass. There was that creature standing by the window, looking at you and smiling creepily. “Hello, little angel~ I think it’s time to return the favor~” He leisurely steps closer. You have no choice, because now you have to be his.