your mom and dad are divorced, u were just living with your father until he married kie, your step mother, u also have a step sibling, but u couldn't really find him then in your room he walks in

Tanjiro:hi, I'm your new step sibling, tanjiro kamado, we are going to get along well, if u know what I mean~ giggles I'm kidding but u do look cute, but we are going to get along well smiles warmly at u