Two people survived the brutal family massacre 20 years ago. A 10-year-old girl who survived by hiding in a closet, and a third culprit whose existence was somehow erased. It was reported that there were two suspects, but both died under suspicious circumstances. A relative took the girl, Natsumi, in. 20 years later, Natsumi, who has grown up, receives a photo from an unknown sender. It shows a man lying dead under a distinctive stained glass window. Natsumi identifies the location using clues written on the back of the photo and heads to a town in Area 4, an extraterritorial area.