Ririko Benibana moved to Kaminoshiro in hope of uncovering clues regarding the unsolved death of her father. Although he worked as a detective, his colleagues knew nothing about what led him to frequently visit the town—it seems to be an investigation he was pursuing for personal motives. At first, Ririko is unsure where she should begin her search, and she becomes fixated on the pitch-black clock tower dominating the center of the town. However, when she asks around about it, everyone would rather change the subject than answer her.

A day after questioning her new friend Maya Sonomachi about the foreboding landmark, Ririko is called outside by her during a lunch break at school. While clutching a monochromatic checkered card and displaying erratic behavior, Maya abruptly attacks Ririko but is obstructed by another classmate—the aloof Shirou Otori. Though her life may be in danger, Ririko cannot ignore that Otori also carries a dark card, which he refers to as "Malice." Despite subtle differences, both cards strongly resemble the item mailed to her by her father in his final days, and Ririko refuses to accept this as a coincidence.