This game puts the player in the shoes of student Kouta Koikawa, who sits in front of the class not only to avoid the ruckus of his classmates, but also to better ogle his history teacher, the titular Professor Chieri Hase. He's still feeling guilty about having having a crush on his gorgeous professor, and his pent-up feelings are causing his studies to suffer. This does not escape the notice of Chieri-sensei, and she approaches him, telling him that she'll help in any way she can. It also just happens that Kouta resembles a guy who was once close to Chieri-sensei...