Kana is a married fitness instructor at a rural gym. Though her marriage has gone cold, she keeps the truth hidden from the rest of town. A local wife refers a middle-aged man named Ippei to the gym, and Kana grows increasingly attracted to him as their training sessions continue. She begins seducing him with her toned, tanned body, and the guilty thrill of their secret affair draws both of them deeper into a relationship devoted to sex and draining him dry.