It's been a year since her husband left her. Makiko has been acting strong in front of her son, but at the same time, she spends her days masturbating to ease her loneliness. Her son, unable to bear seeing her like that, decides on her 20th birthday to support her not as his son, but as a man from now on. Makiko is confused when her son forcefully embraces her and caresses her, but her starving body refuses to reject him. If it's just once... Makiko decides to accept it. But her son is an insatiable stamina, able to ejaculate multiple times in a row...