Darker than Black is a scifi action thriller. It’s a 25-episode series (arguably 24 eps, since the 25th is more of an omake, or side-story, set within the series after it’s been completed–similar to episode 25 of the first xxxHolic anime) that’s set in a slightly-futuristic Tokyo.
Ten years before the opening of the anime, a phenomena occurred in Tokyo and South America–two “gates,” the Heaven and the Hell gate, suddenly appeared. These wrecked havoc on the natural order, putting out the stars and replacing them with fake stars, each of which indicated a ‘contractor,’ someone who is no longer human and who has special abilities, such as the ability to control gravity, the ability to turn their blood into explosives (seriously), or the ability to travel through time. The name comes from the fact that these people are tied to ‘contracts’–they have to fulfill certain actions each time they use their powers, or they risk severe pain or potential death.
The story focuses on Hei, a Chinese contractor for a group known as the Syndicate, who’s working in Tokyo along with his team: a fellow contractor, Mao–who has the ability to jump into animal bodies, but who lost his original, human form and is now predominantly in the body of a cat–Yin, a “doll” (another consequence of the gates–dolls are mediums who can do reconnaissance by sending out spirits via different methods. Yin’s medium is water; others include glass and telephone lines), and the team’s handler, Huang. While the team is initially stationed in Tokyo to carry out hits ordered by the Syndicate, they slowly get embroiled in a greater political struggle that’s playing out between multiple governments and groups around them–a struggle that ultimately has ramifications not only on the team, but on the very existence of humans, contractors, and dolls.
The original anime ran in 2007, and was licensed for English by Funimation, while the two volume manga is translated by Yen Press. There are also a couple sequels–two OVAs (Original Video Animations, or three-episode standalone storylines) and a second anime–but I haven’t seen those, so I can’t say much about them!