text: The series was adapted into two manga series, which were serialized in Kadokawa Shoten's Monthly Asuka and Square Enix's Young Gangan, respectively. A sequel to the anime series, Darker than Black: Gemini of the Meteor, was broadcast for twelve episodes from October to December 2009. In the sequel, Hei trains new Contractor Suo Pavlichenko and searches for his former ally Yin. DVDs of the series included original video animations titled Darker than Black: Gaiden exploring Hei and Yin's relationship between the first and second seasons. In North America, Darker than Black was licensed by Funimation.
  The series was created by Okamura, who was inspired by ninja and spy stories based on ideas he had after creating Wolf's Rain. In contrast to Wolf's Rain heroic cast, Okamura wanted flawed and violent heroes such as the Contractors. While Okamura penned most of the series' contents, he left freedom to other writers, most notably Shōtarō Suga who takes over the work of main writer in the second half. Critical response to Darker than Black was generally positive for its handling of Hei and the other Contractors who fight each other though there was expressure of confusion in regards to the setting and ending.