In the autumn of 2018, Kosuke Mizushima is ready for the wedding. The bride in the wedding hall is Mana Hayase. The sight of her makes him remember the days he had with her those ten years ago. Back in high school, students are busy preparing for exams, but problem student Kosuke, whose grades are poor, is busy enjoying time with his classmates Kotone, Kento, Kazuki and Yohei. His teacher sends Mana, a student of excellence, to sit with him, so she can guide him in homework.