Yumi is working with her husband today at a small town factory that has been supported by two couples and several employees. Recently, her son Satoru helped out at the factory, and they seemed to be very close to each other. However, Yumi and Satoru had a forbidden relationship, hiding from her father and loving each other. The two are absorbed in the "immoral pleasure" that no one should know, and their obscene acts escalate in search of thrill and pleasure.
