The boy called Ishibashi Eita inherited his father's lecherous ways. The world of sexual knowledge that Eita talks about stimulates the instincts of his best friend, Mamoru, and draws him in. Eita shows Mamoru erotic books when he comes to stay at his house, and when Mamoru stays at Eita's house, he receives a culture shock when he catches a glimpse of his parents engaging in sexual activity. Eventually, they both become interested in sex and target their new teacher, Hoshino Miharu, with their mischievous behavior. She is a virgin and becomes the subject of Eita's naughty games.