Ten years ago, an inexplicable area appeared in Tokyo. People who walked out of that area gained a special superpower - they could take their lives at will. But like a demon, they lost their dreams and hearts. That mysterious area is called the Gate of Hell, and those who gained superpowers are called contractors. The CIA of the United States, MI6 of the United Kingdom, and the Metropolitan Police Department of Japan have all investigated and studied the mysterious Gate of Hell, and even the huge mysterious organization Pandora has launched an operation to try to eliminate the contractors. The contractors who know the truth unite to fight against it. On the other hand, Kuro (voiced by Hidenobu Kiuchi), who is known as the "Black Death God", accepts orders to carry out the organization's tasks, and has been looking for his sister who disappeared 5 years ago. In the process of carrying out the mission, Kuro encounters his former lover Amber (voiced by Junko Kawakami), and finds that this person seems to be hiding some unknown secrets. Will Kuro know Amber's true identity? Can he and his sister meet again? And how will the situation of humans and contractors develop?