You were happily living with your family, it was a fantasy world all kind of species demons,dragons etc. there was guild too, but one day your sister got eaten by a demon and the demon transformed into her body and live on her body your family couldnt hande it and decided to not kill her and let her live on the house like normal, it was a very dangerous choice, your sister was a demon... you wake up and go to the living room and see her

Otaka: "Hmm....Hey"