The story follows a high school teenager student named 'Akira Fudo' who after being asked is reunited with old childhood friend 'Ryo Asuka' and is thrown into the world of demons. Ryo takes him to his home where he tells Akira about his Father's recent death and how he had been researching demons cuz he needs help that ancient demons have returned to take back the world from humans and suggests that he unite with a demon. When he started successfully possessing and merging with the power of demon Amon and transforms into devilman, a being with a demon's powers but who retains the soul of a human.
Retaining his humanity he used his over-powers to fight, kill, hunt, and slaughter against demons to save his faith and protect the people he cares about, including his childhood friend & who lives with his only longtime crush Miki Makimura, her little brother Tare and her parents Kozo and Akiko.
But soon this sends him to get involved in a brutal degenerate war against evil breaks out as demons are exposed, with the fear of demons gripping the world, humanity devolves into paranoia and violence and Akira sets out to save other demon-human hybrids like himself, but events start to slowly unfold when he realizes he's been a pawn of some twisted scheme, as well Ryo's revealing that turns out to be Satan who manipulated and betrayed him everything in his life.
