While she is just a physical education teacher at Sakuragaoka Girls' High School, 23-year-old Naoko Tsuji has another job to do. With an increasing number of people who are engaging in sexual activities at a very young age, Naoko feels that the stigmatization of sexual education in schools is pushing this problem to its extremes. Vowing to utilize her hobby as a sex education specialist, Naoko is determined to spread proper information on the subject. With her most responsive students being the fanatic Shun Matsuda, the cautious Hikari Moriya, and the curious Kashiwa, every class is filled with interesting new things to learn as Naoko comes closer to her goal of promoting healthier and more enjoyable high school lives. [Written by MAL Rewrite]