The story follows Mizuki and her two friends, Riko and Reika, who she meets after moving to a new high school. After students begin receiving mysterious chain mail text messages from an anonymous sender, the three girls decide to investigate.

The story follows Mizuki and her two friends, Riko and Reika, who she meets after moving to a new high school. After students begin receiving mysterious chain mail text messages from an anonymous sender, the three girls decide to investigate.