Following the war, the city is filled with numerous "Extends," individuals whose bodies have been altered to serve as hazardous weapons. Inui Juuzou is one such Extend; he lacks any recollection of his life or physical form prior to his head being converted into a firearm. Oddly, his gun-head is constructed so that the trigger can only be pulled by someone standing behind him. Juuzou earns a living by handling cases related to Extends within the city, aided by Mary, a bright young woman whom he has taken under his wing.