Mio becomes an orphan after her mother dies and suddenly is taken in by a man claiming to be her father. She is then used as a tool for a political marriage. As a condition for marrying into the Ichijō family (which has served as imperial exorcists for generations), she is commanded to produce a male heir within one year. The head of the Ichijō family, Kazuto, shows no interest in her — barely interacts, no affectionate words. Mio is told that if she fails, her fate will be worse than death. In the midst of her despair, she discovers a profound secret of the Ichijō household. Also, she learns she has a special power connected to that secret. As Kazuto’s attitude slowly begins to change, the true complications of their marriage and her identity begin to surface.