Her husband has taken up residence with a mistress and never comes home, leaving Sanae with only her son to support her. One day her son brings over an older girlfriend and says he wants to marry her. Sanae is shocked, and is so flustered she can't find the words to express them, so she asks him to go home for the day. Her son follows her out the door. Suddenly feeling lonely, Sanae begins masturbating. Then her son's friend comes over, saying that he'd been invited to a family party...