Takuya, the eldest son, catches his mother secretly masturbating while reading a porn magazine. Shocked yet aroused by the sight, Takuya gives in to his desires and ends up having sex with her. Afterward, their relationship quickly turns tense and strained. Trying to make sense of his emotions, Takuya confides in his younger brother, but instead of offering calm advice, his brother grows jealous and confronts their mother himself—plunging the entire situation into even greater chaos.