Hitomi, the mother, becomes aware of the seriousness of Japan's declining birthrate and speaks directly to her son Makoto. She explains how the aging population is growing and the economy is beginning to collapse, emphasizing the importance of sexual education. As she actively teaches sexual knowledge, her mother takes on an almost missionary demeanor. Makoto, a virgin, and Jiro, the boy next door, submit themselves to their mother's strict yet gentle guidance, gaining new knowledge and experience.