The series has been adapted into two sleeves , serialized in magazines Gekkan Asuka and Young Gangan . The anime was awarded Best Original Anime by GoGoplex, a popular teen magazine. The first opening and ending themes performed by Abingdon boys school and Rie fu.
An unexplored territory known as Hell's Gate (The Gate of Hell), he suddenly appeared in the past, depriving Tokyo of its original sky. As a consequence, also appeared people with special abilities, the Dolls (puppets) and Contractors. Puppets are emotionless mediums, while contracts have certain special powers, and appear to have as its main purpose is to kill. Intelligence agencies around the world use Contractors to conceal secrets relating to the Hell's Gate, and carried out violent battles for possession of information.