After her divorce, Anna Hoshia lives alone with her son, Shuichi. As Shuichi reaches adolescence, he gradually develops an interest in sex, and due to their single-parent household environment, finds himself increasingly attracted to older women. One day, Anna accidentally discovers Shuichi masturbating while watching an incest-themed adult video. Shocked and upset, she harshly scolds him, causing Shuichi to decide to run away from home. Several days later, after he safely returns, Anna invites him to bathe together. As Shuichi opens up, expressing his deep affection for his mother, Anna feels her emotions stirring once again.