In the year 20XX, as a measure to combat the serious declining birthrate in Japan, the compulsory education curriculum is reformed to "increase the time students spend holding penises rather than pens," and newly appointed female teachers are hired to teach the school's traditional sex education curriculum. For the sake of the male students who represent the future, they get completely naked and experience "the differences between male and female genitals" and "the mechanism of pregnancy" with all five senses, teaching them how good sex feels.