Yukino is a housewife living with her son Satoru and her husband. After 24 years of marriage, her days are filled with family life. However, one day, her husband's younger brother Takashi visits the house, and Yukino gives in to his physical advances—they already have a secret sexual relationship. That night, Satoru notices a change in his mother's behavior and discovers the affair between her and his uncle. Overcome with intense jealousy and inner turmoil, he spirals into emotional conflict. A shocking turn of events awaits as family bonds begin to unravel.