Before the new semester begins, Misaki Fujioka decides to drop in on her twin sister, Mei Misaki, who's residing in Yomiyama City. Together, they spend their summer days exploring the city's attractions, from shopping centers to shooting stalls. While perusing Mei's basement, she confesses being worried about the new class she's been assigned, which is rumored to be cursed. To liven things up, the sisters go to an amusement park. Yet, Mei's excitement fades when she sees the grim aura of death looming over her sister, warning her of a looming tragedy.