The story is based on the guidebook "Health and Physical Education for 30-Year-Olds", published by Mitsuba and Ichijinsha. The guide targets men in their 30s who have not had any romantic or sexual experiences with women. Our protagonist is Imagawa Hayao, an unmarried 30-year-old virgin. One day, a cupid is sent from above, determined to help him lose his virginity. What follows is a tale of an innocent love between a single 30-year-old man and a single 30-year-old woman.