Shortly before the start of a new semester, Misaki Fujioka visits her twin sister Mei Misaki in Yomiyama City. The girls make full use of the last days of summer, roaming around a heat-weary town and visiting various places including a shopping center and shooting stall. When they prowl around her basement, Mei expresses uneasiness about her new class, which is said to be cursed.

Craving more entertainment, the twins decide to pay a visit to the local amusement park. But the leisure of a sleepy summer day could soon turn woeful as Mei sees the color of death on her sister—an unmistakable omen that a tragedy is bound to strike.