Yuki and a group of friends discover the reflection of a corpse in the bathroom mirror at their school. What they first dismiss as a prank soon proves to be the beginning of a series of gruesome and violent events that pull them into a nightmare they cannot escape. The central story unfolds in a seemingly ordinary school setting, a place where the boundary between the living and the dead becomes disturbingly thin. Alongside this narrative, the volume collects three other tales of horror. One follows a girl whose striking beauty makes her the target of a relentless terror campaign. Another features a student who is cruelly bullied by a teacher and, after dying, returns to exact a chilling revenge. A third story centers on the mystery of classroom 3.7, a room from which students enter but never leave, vanishing without a trace. The manga explores themes of innocence crushed by evil, the consequences of cruelty, and the supernatural forces that can arise from everyday places and relationships. The characters are ordinary students caught in extraordinary, terrifying circumstances, each facing a distinct form of dread that stems from the dark side of human nature.