Devilman Complete TV Series - Japanese Ver.
A long time ago, Demon ruled the land. Life for them was survivial of the fittest and they constantly fought amoungst themselves. After a cataclysm, they found themselves to be imprisoned in ice, sleeping until the fated Armagoddon Xofu, they have awakened and are wrecking honor on humanity.
In order to fight a demon, you must become a demon. A Demon may possess a man's body and be in complete control of it. It takes a pure man to retain control of this hybrid form. Mankinds savior is a devil with a soul - his name is Devilman.