Takuma is surprised to see his old friend Mayu at the high school entrance ceremony. As kids, they promised one another that they would get married.

Takuma and Mayu decide to be just friends. Meanwhile, Kou, the student body president, comes up with a plan to attract Mayu's attention.

Mayu is emotionally confused when she sees Teru try to kiss Takuma. Feeling upset, Mayu erupts at him as they work together in art class.

Takuma visits Teru in the hospital to tell her his true feelings, but she collapses before he can finish speaking. Meanwhile, Kou approaches Mayu.

Kou and Mayu get into a traffic accident. Takuma runs to the hospital to find Mayu unharmed. Filled with regret, he pours his heart out to her.

When Mayu is pursued by a man late at night, she calls Takuma for help. Though Kou saves the day, Takuma's mom is upset by Mayu's careless behavior.

Takuma learns that Kou, who is brain dead, will be the donor for the heart transplant. He rejects the proposed surgery and leaves the hospital.