Yui was living a happy married life. Due to her husband's job transfer, they moved to his parents' house temporarily until they could find a new home near his new workplace. Her husband has a younger brother who is a ronin (a student studying for entrance exams), and feeling the pressure he faces from the family, Yui decides to help him with his studies... However, the brother-in-law becomes attracted to Yui's body, and his feelings take a wrong turn... He begins to show his true colors toward Yui...