Yumeo, a high school student, is ordered by his mother, who is a succubus, to sneak into the bedroom of one of his female classmates late at night. He believes the girl to be an experienced and promiscuous individual, but upon entering her room, he makes a startling discovery that completely contradicts his expectations. Contrary to the rumors and her outgoing persona, the girl is revealed to be surprisingly innocent and naive. The story follows the supernatural and comedic situations that arise from this midnight encounter, blending ecchi and slice of life elements as Yumeo navigates his mother's unusual demands and his classmate's hidden true nature. The narrative is set in a contemporary Japanese high school environment, with the primary conflict revolving around Yumeo's secret nocturnal missions and the evolving, often awkward, relationship with the girl whose reputation does not match her personality.