Darker Than Black (2007)

In a world altered by the appearance of two mysterious areas, known as Heaven's Gate and Hell's Gate, individuals known as Contractors gain supernatural abilities at the cost of their humanity. Hei, a masked operative known as the Black Reaper, works for a shadowy syndicate, taking on dangerous missions while uncovering secrets about the Gates and his own past. The series blends espionage, action, and existential themes, creating a dark and atmospheric narrative.