This incident happened when Daiki, a second-year student attending a public high school, was about to celebrate the second anniversary of entering into a relationship with his childhood friend Reina, with whom he had confessed his feelings. The long and enjoyable days of summer vacation had ended, and a few days into the start of the second semester, on a day when Reina had arrived early to school for student council duties, Daiki, who had arrived at school alone, found a lost item while changing into indoor shoes at the shoe lockers near the front entrance of the school. This event shattered their daily life and led to the unraveling of the relationships among childhood friends.