After being evicted from their long-time apartment in Tokyo, Seiko Shiratori and her son move to her late husband's family home. While enduring constant sarcasm from her husband's older brother, Seiko continues to care deeply for her son. Her devoted presence captivates her brother-in-law, who, exploiting their vulnerable situation, begins pursuing her voluptuous, mature body. Night after night, Seiko is forced to obey his demands—acts her own son witnesses in secret. A story unfolds intertwining maternal bonds, family conflict, and forbidden desires.