Darker Than Black Vol 1

About Darker Than Black

Kana Shinou's father died in a terrible tragedy a year ago, but when she sees him on the street one day, she's convinced of her long-held belief that he's still alive. Subsequently, she witnesses a fight between two superhumans, known as Contractors. Her memories of the encounter are erased, but they soon come back and she ends up teaming up with one of the combatants -- a young, stoic man named Hei. Together, the two search for answers regarding her father's deceit and the dangerous organization he's become associated with.

Source: Anime News Network Encyclopedia