Rika likes teacher Aisaka very much. When she is alone with him, she declares her love to him. But he gave her the cold-shoulder. Deeply disappointed, Rika accidentally tips over bottles of chemicals in the science room, and is injured on the back. Aisaka feels that he is responsible, and announces his engagement to her. Rika feels sad about his tenderness, because she thinks that it is only the because of her injury.