The limited edition comes with a B2-sized tapestry with a newly drawn illustration, an original soundtrack, and an acrylic key chain with a newly drawn illustration. (CERO Age rating: To be determined) [Machine Translation] The world has collapsed due to the Great War, and the setting is Lagoon, an evacuation site for children only. Kai, a mercenary boy who lives in Lagoon, an abandoned amusement park, meets a girl named Mio. She is a clumsy girl with silver hair, a lisp, and cannot wrap a bandage even though she is good at shooting. There, Kai learns Mio's secret. Mio has been fighting to find a corpse for a certain purpose. Kai, who sees himself in her image, allows Mio to stay at his house. Kai's childhood friend, Dr. Kai, also lives there. The protagonists enjoy a brief respite in a collapsed world. However, these happy days are not forever. The time limit is approaching every minute...