After the war, there are many "Extends" in the city, people whose bodies were modified to make them into dangerous weapons. Inui Juuzou is one... more>> of them, and he has no memories of his life and body before his head was transformed into a gun. Strangely enough, his head-gun is designed so that only someone behind him can pull the trigger. Juuzou makes a living by taking on cases involving Extends in the city, and he is assisted by Mary, an intelligent young woman that he has taken under his protection. <<less