A new and deadly breed of covert agent walks the streets. Known as Contractors, these assassins and spies wield bizarre supernatural powers to carry out the dirty work of others. They thrive in the underworld, between rumour and reality, their loyalties always in question.  In Tokyo, an impenetrable field known as "Hell's Gate" appeared ten years ago. At the same time, psychics who wield paranormal powers at the cost of their conscience also emerged. Hei is one of the most powerful of these psychic agents, and along with his blind associate, Yin, works for one of the many rival agencies vying to unlock the mysteries of Hell's Gate.