Hei is a fictional character from Darker than Black. Codename "Hei", the main protagonist, is an elite Contractor, with the Messier Code BK-201. Operating as an assassin and stealth operative for the syndicate, Hei seems to be involved with many incidents involving contractors. He is known as Kuro no Shinigami (The Black Reaper) to other contractors. This is because of his appearance during his missions, where he wears a distinctive mask and a black coat. This character is popular among cosplayers. It can be portrayed by wearing cosplay Hei costume and cosplay Hei wig. This character is always present in a Darker than Black cosplay.