Heaven's Gate arrived in South America ten years ago, while Hell's Gate came in Japan ten years ago, obscuring the once-familiar night sky with an unpleasant skyscape. These Gates are places where the rules of physics are disregarded for unexplained reasons. Contractors evolved with the arrival of the Gates, who are granted extraordinary talents in return for their humanity. Section 4 Chief Misaki Kirihara finds herself at conflict with a famed Contractor dubbed Hei in the Japanese city bordering Hell's Gate. In the subterranean realm, Hei is known as "Black Reaper," and he, like his colleagues, executes tasks for the enigmatic and brutal Syndicate while steadily peeling back the dark layers masking a diabolical conspiracy that threatens the very existence of Contractors.