The setting is a post-apocalyptic time when a strange spatial accident has opened two “gates”, Heaven’s Gate in South America and Hells’ Gate in Tokyo, and altered the sky, replacing the known stars with a different star pattern. The Gates are cordoned off by massive walls and are inaccessible to the public. The spatial anomaly that opened them also introduced new, phenomenal powers to certain individuals who form “contracts” in exchange for the power. These “Contractors” have specialized supernatural powers, but are no longer considered quite human. In exchange for their powers, they seem to lose human feelings and also whenever they use their power, they must perform a ritualized, compulsive “punishment” which is part of their contract. For example, chain smoking, eating a certain food or performing a meaningless task are all compulsions of the various Contractors. Also each Contractor is somehow linked to a specific star in the new sky, which reacts when that Contractor uses his or her powers. So the Contractors are also referred to by their star Messier catalog number. Most of the Contractors are employed as assassins or agents for some government or shadowy conglomerate.
This series follows the exploits of a man named Hei. Hei is a Contractor, number BK-201. In fact, he may be the original Contractor. When he’s in Contractor mode he wears a mask and is known as the Black Reaper. He is accompanied in his tasks by a cat named Mao who is a body-switching contractor who lost his original body, and a young girl named Yin who is actually a Doll, a non-human construct used for various purposes.
The series follows Hei through a string of tasks for his employers, as well as through his interactions with everyday people, so it's set up as a series of mini-arcs. Along the way the background is established. Several arcs deal with the premise that Dolls can have human feelings and deserve a chance to live a life. One of the deeper plots is that the spatial accident which made Hei a Contractor and created Contractors in general, also resulted in the death, or at least the disappearance of Hei’s sister, Pai, who he is semi-looking for throughout the series.
As the series goes along, Hei-tachi begin to act against the wishes of their employer organization, The Syndicate. Late in the series, the Contractors discover that the Syndicate is attempting to close Heavens’ Gate as a way of destroying all the Contractors. Hei and the majority of the other Contractors band together and mount an attack on Heaven’s Gate to stop it being closed. The story ends with only Hei and Yin actually managing to make it all the way to the Gate itself, and once there Hei must make a decision for all Contractors – close the Gate and end Contractors or keep it open and let them continue. He leaves it open.
This is where the first 26 episode season ends. There is also a second season of 12 episodes and four OVA episodes that cover events that occur between the two seasons, but I liked the first season best. Hei is a likable character, and much too human to be a Contractor. He always goes with his own sense of right and wrong rather than what he’s told to do by his employers, which is why he’s often in trouble. Plus the series music is done by Yoko Kanno who is my favorite composer. It’s definitely worth watching.