One day, while walking home from work, impoverished high school student Hirazono Satsuki discovers a girl lying in a garbage dump. He takes her in, and she introduces herself as Riene, an exorcist. Riene is searching for a person named Satsuki who once took care of her, and she quickly identifies Satsuki as that same individual—though Satsuki is male, while she had been looking for a girl. The reason for the confusion lies in Satsuki’s childhood, when his older brother forced him to dress as a girl, leading Riene to remember him as a female caretaker. Before Satsuki can send her away, the two are caught in a binding marriage curse that forces them to perform a marital act once a month; if they fail, their souls will be drained. Riene, a cheerful and openly perverted exorcist who shrinks into a chibi form whenever she thinks lewd thoughts, moves into Satsuki’s home and later enrolls at his school, causing constant chaos. Meanwhile, a malicious spirit possesses Satsuki and manifests as a dangerous alter ego, adding a supernatural threat to their daily lives. Their relationship deepens amid comedic misunderstandings and escalating romantic tension, complicated further by the arrival of Riene’s eccentric older sister Marche, who was formerly male. As the expiration of the marriage curse approaches, Riene is called back to her convent, and the pair must decide whether to break the spell or fully commit to each other. The story concludes with the curse resolved and the two solidifying their bond, bringing their unusual cohabitation and romantic journey to a close.