With their school shutting down for good, the students of a small town were heading for different directions in life. For Minase Tamaki, who was staying in town to find a job, it might be the last time she sees her crush Shindo Yuuma, who is moving to the city to attend a new school. She asks him to do a little prayer that is supposed to help people cross paths again even if they become separated. But her classmate, Yuzuki Erina, overhears their conversation and, out of jealousy, decides to ruin her plans by inviting their entire class on what was supposed to be an intimate spell.
As soon as the charm goes off, the ground splits in half, swallowing the entire class and, when they wake up, they find themselves in an old school campus. Unable to find a way out, they wander the corridors, trying to figure out where they are. But it seems that the building isn’t as abandoned as they thought it was and, in fact, something evil is lurking in the shadows.