Trying to relieve her lack of exercise, Mizuho, a slightly mature woman, began marathon training with her older boyfriend. However, since he was an experienced runner with an overly fast pace, she couldn't keep up and collapsed. As a result, she ended up resting temporarily at the coach's place. To loosen her muscles, the coach began giving her a massage. Starting from her calves, moving up to her thighs, buttocks, and gradually approaching her groin area, he intensified the stimulation. Unable to endure the sensation, a wet spot began to form on the crotch of Mizuho's shorts. Sexually aroused, she started having an affair with the coach, leaving her boyfriend behind. Mizuho possessed an exceptionally attractive body, which the coach passionately used to his satisfaction, leading to an increasingly lewd situation. Her actions, abandoning her boyfriend, carried a seductive and alluring charm.