Niiya Teiichi, a freshman at Seikyou Academy has managed to get himself lost inside the abandoned old school building. If you stand in front of a big mirror somewhere in the building and look over your shoulder, it's said that you'll be dragged into the mirror by a ghost. When Teiichi finds the mirror, he meets and is escorted back outside by a girl called Kanoe Yuuko, who introduces herself as the ghost of the old school building. However, Yuuko can't remember anything about her death and so she starts a club with Teiichi to figure out the cause behind it. One day, a girl called Okonogi Momoe turns up to the club asking for help, to get rid of a spirit that she had "summoned” during a game of Underground Demon that went wrong. Teiichi realizes that the whole game is based on self-suggestion, and stages a scene to get rid of the "spirit”.