Akira is just another normal kid in modern-day Tokyo, until an old friend of his, Ryo, shows up and turns his world upside down. Akira learns that there is an upcoming war of demons on humanity and he has just been enlisted for a major tour of duty. But the only way to fight a demon is with their power, so Akira and Ryo risk a dangerous ceremony in an attempt to create humanity's only hope: the powerful Devilman.

Fear runs rampant throughout Tokyo with the revelation that demons in fact exist amongst us. Paranoia and the darker side of humanity boils onto the streets as people turn on one another, suspecting that anyone could in fact be a demon hiding in human clothing. Amidst the growing tensions, tragedy strikes Akira causing his mind to snap, retreating into his subconscious, allowing his Devilish alter-ego Amon to break free from Akira's cage of flesh and wreak havoc on both human and demons alike.

Akira Fudo learns from his best friend Ryo Asuka that demons will revive and reclaim the world from humans. With humans hopeless against this threat, Ryo suggests combining with a demon. With this, Akira becomes Devilman, a being with the power of demon but with a human heart.

After discovering the existence of demons in Tokyo, the original 00 Cyborg crew led by Dr. Gilmore find themselves in conflict with Devilman, a strong demon believed to be in league with the war-profiteering terrorist organization, Black Ghost. Meanwhile, a bigger threat emerges when Dr. Adams, a Black Ghost scientist unleashes his new line of high-teen 00 Cyborg models against 009 and his friends.

Akira is just another normal kid in modern-day Tokyo, until an old friend of his, Ryo, shows up and turns his world upside down. Akira learns that there is an upcoming war of demons on humanity and he has just been enlisted for a major tour of duty. But the only way to fight a demon is with their power, so Akira and Ryo risk a dangerous ceremony in an attempt to create humanity's only hope: the powerful Devilman.

Akira Fudo (aka Devil Man) fights more demons trying to kill him. The strongest enemy sent from the demon's world is Silen, the demon bird.