After remarrying, Shoko and her husband began family life each with a child from a previous relationship. Three years later, their marriage has become sexually stagnant, and her stepson begins to develop a strong interest in Shoko's voluptuous body. Pressured by her own sexual frustration, her stepson's "maternal dependency," and growing desires, Shoko resorts to sexual relief with him. She gradually deepens their secret relationship, hiding it from the rest of the family.