Maki Motokawa, the mother of Kent, worries about her son's future after he repeatedly fails his college entrance exams and remains a perpetual ronin student. She helps him study every day, but as Kent reaches adulthood, his attention begins shifting from books to women's bodies, and his sexual desires gradually intensify. Noticing this change, Maki decides to take an active role in her son's sexual education, stepping beyond the boundaries of ordinary motherhood. As maternal love intertwines with her hopes for her son's future, a new and forbidden relationship begins to unfold.