A few years after marrying her husband who came to work from the countryside, Eriko has been living happily in the city, but she is worried about her stepson Kyo, who her husband left behind in his hometown... One day in the middle of a record-breaking summer heat wave, Eriko decides to return home with her husband. However, for Eriko, who is used to city life, living in a wooden house without air conditioning is unimaginably hot. Sweat running down her neck... sweat floating on her chest... the obscene sweat that covers her whole body leads the stepmother and son into a twisted relationship...