Momo and Okarun go to the same school – and that's where their similarities end. High school beauty Momo believes in ghosts and thinks aliens are nonsense. Outsider Okarun, on the other hand, firmly believes in extraterrestrials and considers ghosts to be silly. So they bet on who is right: Momo is supposed to visit an abandoned hospital, also known as an alien hideout, while Okarun is to explore a haunted tunnel. But what happens next makes even their wildest imaginations seem mundane.