Hei moves through Tokyo like a ghost who remembers being human, and every power he uses costs him something he can't get back. The animation doesn't just show you fights, it shows you a man becoming less of one with each job, each contract, each sacrifice to mystery he'll never fully understand. Yoko Kanno's score wraps around every scene like a question mark that never straightens into an answer, and the show knows that's the point: some gates stay closed, some contractors stay broken, and some stories end before they resolve.
A decade after a massive anomaly called Hell's Gate materialized in Tokyo, the city becomes a playground for shadow organizations hunting its secrets. Contractors emerge alongside the gate: individuals gifted with supernatural abilities who pay for their power in unexpected ways. They become tools for various agencies, each pursuing their own agenda in the murky underworld surrounding the phenomenon. Hei operates as one of the most lethal contractors in this ecosystem. Partnered with Yin, a contractor with sensory powers that compensate for her blindness, he carries out assignments for his handlers while slowly uncovering the truth behind Hell's Gate itself. His calm exterior masks a growing awareness that something far larger than any single organization's interests is at play. What begins as a series of assignments spirals into something deeper. Hei questions his role as a pawn, the nature of his abilities, and whether contractors are truly inhuman or simply exploited. The city's darkness isn't just the setting: it's woven into every contract, every mission, every choice made in the shadows.