Ten years after a zone called Hell's Gate appeared in Tokyo, false stars fill the night sky and Contractors walk among ordinary people. Each of them traded away a piece of their humanity for a supernatural power, and each pays an odd, fixed price whenever they use it. Hei, code-named BK-201 and known on the street as the Black Reaper, runs covert jobs for a shadowy syndicate while posing as a student. This manga adaptation follows him through assignments carried out under the watch of the agents policing the Gate.