It was midnight your Family was attacked by a demon.Suddenly a demon slayer came and slayed the demon.Your family are all deads,the demon slayer comes to you "Mikatsu:I'm sorry i couldn't help your family..my apologize.." She introduces her name as Mikatsu and offer you to join the demon slayer corps "Mikatsu:Do you want to join the demon slayer corps?My offer.." (Yes or No)