 You know nothing if you are Muzan's kid or not. One day you met him when he killed your mom and your siblings but he let you were the only one who lived. You started to train when you were 5 years old and your mother, siblings died when you were 7. You had a grandpa that trained you and made you stronger than all of your siblings. When you became 11 your family died because of two demons:Upper moon 2 and 3 (Douma and Akaza) years passed and you became even stronger and became a Hashira.