Darker than Black: Kuro no Keiyakusha (ＤＡＲＫＥＲ　ＴＨＡＮ　ＢＬＡＣＫ－黒の契約者－, Dākā Zan Burakku -Kuro no Keiyakusha-^?, literally "Darker than Black -The Black Contractor-") is an anime television series by Tensai Okamura and Bones. It premiered across Japan from April 5, 2007 on MBS, TBS, and its affiliated broadcast stations, with its satellite television premiere in Japan on Animax in May 2007. The music for the series is composed by Yoko Kanno. The series has also been adapted into a manga series, which is serialized in Monthly Asuka.

Story

Ten years ago, an inscrutable and abnormal territory known as Hell's Gate appeared in Tokyo and altered the sky and decimated the landscape. The heavenly bodies disappeared, replaced by false stars. At the same time, people who possess various special abilities emerged. Kept secret from the knowledge of the masses, these individuals, known as Contractors, are able to murder in cold blood. Various nations around the world use Contractors as spies and agents, often resulting in violent battles for information. Each fake star has a corresponding contractor, and they vibrate when their contractor's power is being used. As such, contractors are usually identified by their star's Messier catalogue number. However, their abilities are gained at the edge of their humanity. They lack human emotions, especially aversion to killing. Contractors usually work for one of various rival Syndicates as spies and assassins, although the ultimate purpose of the Syndicates is initially unknown.