Hei
His name at his job is BK-201 or Black Reaper but His real name is Hei, which means black in Chinese. Considered to be the strongest Contractor and the most feared, Hei lives two lives in the series in wich he names himself Li Shengshun in his public life, while undercover he is regularly seen as a good-natured, timid Chinese Student with a upbeat, friendly Persona but otherwise generally keeps to himself. and usually doing something such as working or eating huge meals.Hei's other life is of a Contractor called BK-201 With the ability to use electricity. Contractors are said not to have emotions, but Hei seems to have them. He seems heartless at points, but Hei does have a heart. And that is proven by how much he loves his sister he lost when the South American Gate imploded. He deeply cares for his sister, Bai, Before he became a Contractor, Hei was a caring older brother who looked after his little sister, Bai and searches for her after her disappearance.During the "Heaven's War", Bai went missing with the rest of Hei's team. He continued to serve the Syndicate in hopes of finding out what happened in South America's Heaven's Gate, and more importantly what happened to his sister.. but the story goes....so.....You are not doing anything right now so go watch it?!

Anime: Darker Than Black