Akira Fudou, a kind-hearted individual, always had a habit of being too accommodating. When he coincidentally meets an old friend from his childhood, Ryou Asuka, a terrifying reality is revealed to him: demons not only exist, but they also have intentions of taking over the planet.
Driven by his desire to assist Ryou in his quest to save humanity, Akira agrees to attend the infamous Black Sabbath party, infamous for its corrupt and depraved reputation, to merge with a demon. Though at death's door, this event led him to become one with Amon, a demon who even his kind fear. Together, they created Devilman, utilizing Amon's power and Akira's pure-heartedness.
With newfound strength from the combination, Akira commences his fight against the demons in hopes of removing the burden weighing on human civilization.