Shinichi has a wife and child, but finds himself attracted to his mother as a woman. Unable to suppress these feelings, he convinces himself that being somewhere other than home might make it acceptable, and invites her on a hot spring trip. Lying to his family, he creates time alone with her. Though he knows it's wrong, that very guilt becomes the trigger for release. As he penetrates her for the first time in years, she initially hesitates, but gradually loses herself, surrendering completely to pleasure. When their emotions intertwine, the long-suppressed desire erupts—unstoppable and insatiable.