The story follows Takashi, who successfully confesses to Ai, the most beautiful girl in school. However, she sets a condition: they can only start dating after their entrance exams are over. Meanwhile, Takashi's childhood friend Yumi, who is always at his house and believed he would confess to her, is heartbroken. Seeing an opportunity in the waiting period, Yumi proposes a self-serving arrangement: to prevent Takashi from embarrassing himself with Ai, she will give him "special training" to make him a better man. Under this pretext, she forcibly initiates a physical, "training-based" relationship with him. As these intimate sessions continue, the feelings between Takashi and Yumi begin to change, creating a complex emotional triangle.