Read manga: Darker Than Black

manga
Summary:

A young girl's nightmare becomes the search for the truth, a search that leads her to the secret and extremely dangerous world of Contractors and the Hells Gate. Hei and Mao try to protect Kana from the Contractors who are trying to silence her forever, while Kana clings to the hope of finding her father and piecing her life together again. -- Bushido Angel Adventures NOTE: (revised) The story is told much differently from the anime. It is focused mainly on the girl, Kana.