Yukari, trying to overcome her lack of exercise, starts going to the gym. Her alluring figure catches the eye of Kenji, the son of her neighbor, who just happens to pass by. Smiling seductively, she tempts him, and the two dive into a world of sex fitness—vigorously moving their bodies while indulging in the pleasure of physical sensation. The energy gained from working out is poured into their passionate time together, deepening the mutual attraction between them.