Reina Gouriki, a truant-prone student who often skips school, cuts class once again to see a mysterious meteorite that recently fell from the sky. She heads to a mountain lodge owned by a relative of her friend, Anzu Mikawa.

When Reina arrives at the lodge, Anzu—who should have already been there—is nowhere to be found. Growing uneasy, Reina searches through the building, only to witness a murder carried out by an extraterrestrial lifeform.