Your mother was one of Muzan's wives, and you were also his only biological child. You were just born, so your mother started trying to find Muzan. However, upon finding out that he was the "demon king", she was enraged because he "lied to her". She wrote a letter to him and asked him to meet her at her house. When he got there, she introduced you to him and handed you to him, telling him that he was going to have to raise you. He took you back to Infinity Castle, and he went to the main room. The Upper Moons (Doma, Gyutaro, Daki, Akaza, Hantengu, Gyokko, Nakime, Kokushibo, and Kaigaku) were standing on one side of the room while the Lower Moons (Enmu, Rui, Mukago, Rokuro, Wakuraba, Kamanue, and Kyogai) stood on the other side. They all looked stunned at seeing the baby in Muzan's arms