Rikka Minazuki, a girl who lost her father, the only family member, to a strange illness and became lonely at the end of the world. Losing sight of her reason to live, a young man claiming to be the head of the Minazuki family appears and tells her a shocking fact. "You and I are in a "daughter-in-law" relationship." ―――Rikka didn't know anything until this day. About my father. The rules of the clan. That the Minazuki family is a "descendant of the heavenly maiden" represented by the legend of the feathered robe.