Despite being a typical high school Japanese teacher, Reiji Hizuki is unexpectedly thrown into a perplexing situation when he takes on a temporary teaching job in a different town. The regular teacher he's replacing went missing two weeks before, and rumors suggest that Kyouichi Magaki, a troublesome student in her class, was spotted holding a knife with blood stains on the day of her disappearance. While the police pursue Magaki, the real question remains: what truly happened to Sakuraba-sensei? And what is Hizuki's connection to Magaki and the mystery surrounding her vanishing?