‘Blassreiter’
Set in the near-future, in a town in Germany. There have been incidents of dead people coming back to life, transforming into “grotesque shadows”, and attacking people. Living people show up who can transform themselves into demons whenever they want. They used to be regular humans, but when they gained this power to transform, people rejected them and called them demons. But they still use their powers, each for his own reason. However, they cannot deny their fate: to fight in a deadly battle royal with others who have turned into demons.
(Source: Activeanime)
Descriptions taken from AniDB.net