Mai meets Naru while exchanging ghost stories with her friends, and learns her school principal has hired him to investigate an allegedly haunted school building. Mai later causes the injury of Naru's assistant and is forced to stand in as a temporary replacement. The principal also brings in several exorcists and mediums, and more help arrives in the form of a classmate of Mai's, who claims to have the ability to sense spirits.

Each member of the team proposes a different theory as to what is responsible for the odd occurrences. After collecting data overnight, Naru begins to doubt the presence of any spirits and instead theorises that land subsidence is the cause of all the ghostly activity. Mai's classmate, Kuroda, fiercely insists that a poltergeist is at work, and evidence appearing to support her idea soon arises.

After disappearing for a night, Naru conducts an experiment involving all those associated with the case. He implants a hypnotic suggestion in their minds regarding a chair in a sealed room moving overnight. His experiment proving successful, Naru reveals his explanation for the latest developments, correctly accusing one of the group of mimicking a poltergeist's acts. After the conclusion of the case, Naru offers Mai a part-time job at the SPR, which she accepts.