Nakajima Misako wishes to have a close relationship with her parents & siblings, who want nothing to do with the poor girl, who instead makes her do all their work, while they do whatever they want. Growing up in the Taisho Era, the family knew nothing about Kibutsuji Muzan nor the demon race, not even the Demon Slayer Corps, did Misako's family once think that such things existed. However, everything changed on the night of Misako's 13th birthday, when both her mom and dad were turned into demons by the Demon King himself...