Devilman

Akira Fudô (Hisato Izaki) is a gentle, easily rattled teenager whose closest friend is Ryô Asuka (Yusuke Izaki), a brilliant and guarded boy who pulls him into a hunt for demons. A search for a new energy source releases powerful demons that begin taking over human bodies and tearing civilization apart. Hiroyuki Nasu sets the two friends on opposite sides of that war, and what binds them is what the fighting is slowly pulling apart.