Strict mother Reiko has rigorously raised her son Ryota to become a success. But Ryota isn't getting anywhere in life, her husband has grown distant, and Reiko's stress and pent-up sexual desire continue to build. One day, while secretly reading an adult magazine she found in Ryota's room, her suppressed desires suddenly explode. At that moment, Ryota's best friend Atsushi happens to visit and discovers her in the act. Instead of scolding him, Reiko—overwhelmed by years of frustration—gives in to her instincts and begins passionately groping Atsushi's body. This impulsive act becomes the catalyst for a new, forbidden relationship.