Saying farewell to a classmate is never easy, but it is the reality a group of students at Kisaragi Academy must face. In an attempt to alleviate the sadness caused by their friend's departure, they perform a ritual that will bond them all together eternally as friends: the Sachiko-san Ever After charm. But after it is completed, the floor beneath them gives way and they are sucked into a gaping abyss.

After getting their bearings, the students discover their surroundings have drastically changed. While it appears they are still in a school, it is not the one they know; rather, it is a run-down version of Tenjin Elementary School, the place that Kisaragi Academy was built upon after a series of kidnappings and brutal murders led to its demolition. What's more, and frightening, is the appearance of the malevolent ghosts of the murdered children.

As these students navigate this ghostly labyrinth with no escape in sight, they come face to face with the evil that brought them there, and the truth behind the gruesome murders of Tenjin Elementary School.