Guest and Airi Murasame were classmates in high school. Airi was bright, social, and beautiful—the "class idol" popular with everyone. Just before the summer break of their first year in high school, Airi, who secretly harbored feelings for Guest, gathered her courage and invited him to a fireworks festival in her hometown. However, Guest assumed that a girl as out of his league as her couldn't possibly like him, and he turned her down due to a prior engagement with a middle school friend. In the autumn, Guest began dating Airi's best friend after she confessed to him. Airi also tried to give up on her feelings for Guest and dated another boy. Later, Guest's girlfriend told him, "Airi invited you to the fireworks because she liked you," and he realized his misunderstanding for the first time. But it was too late; both kept their feelings buried while they were with other people. Eventually, both broke up with their respective partners, but they graduated high school without ever closing the distance between them, being too self-conscious to act. After graduation, by chance, they both enrolled in the same university. Just before the summer break of their freshman year, Airi invites Guest to her hometown fireworks festival once again. This time, Guest understood the meaning and accepted the invitation.