Sana's father, Minatozaki Nichkhun, is dead. Now she must assume his place as the head of the Fox Clan. But not everyone agree that the girl is fit to fufill this place, putting the heir's life in danger. Enter Minatozaki Tzuyu, Sana's cousin and the best soldier on the clan, designated to protect Nichkhun's daughter from everything that threathens her life. But Tzuyu already have demons of her own to deal with.