Momo Ayase strikes up an unusual friendship with her school's UFO fanatic, whom she nicknames "Okarun" because he has a name that is not to be said aloud. While Momo believes in spirits, she thinks aliens are nothing but nonsense. Her new friend, meanwhile, thinks the exact opposite. To settle matters, the two set out to prove each other wrong—Momo to a UFO hotspot and Okarun to a haunted tunnel! What unfolds next is a beautiful story of young love…and oddly horny aliens and spirits?