Devilman features Akira Fudo, a shy and timid teenager who has gone mountain climbing in the Himalayas with his father. While in the middle of the expedition, both father and son are killed in a tragic accident. Akira's body is found and possessed by the demon soldier Devilman, who uses his new human form as a disguise in order to fulfill his mission of causing chaos on Earth in order to pave the way for a demonic invasion of the planet. Before his mission can begin in earnest, Devilman meets Akira's childhood friend Miki Makimura and quickly falls in love with her. Devilman resolves to protect Miki and humanity as a whole by battling against his fellow demons. Demon Tribe leader Zennon becomes greatly angered at Devilman's betrayal and is quick to send Devilman's former comrades to destroy him. The other demons soon learn that Miki is precious to Devilman and he must now work to protect her, as well as protect himself. Will the power of love be able to overcome that of true evil?

When Ryuu is born his tribe tries to sacrifice him to a Tyrannosaurus named Shirano because of the color of his skin. He is however saved by a monkey who raises him as her own son. Meanwhile Ryuu's mother has left the tribe and is out on a quest to find Ryuu. 16 years later Ryuu meets a girl named Ran who was sold to the tribe Ryuu originaly came from. The tribe is not happy to see Ryuu alive and tries to sacrifice him again, this time by burning him alive. Before they can get the deed done the tribe is massacred along with Ryuu's adoptive mother by Shirano. Ryuu then sets out on a quest together with Ran to find his mother and Ran's brother Don.

Makoto Kubota wandered through life, not taking things too seriously or looking too deep within himself. His job as the head of the Izumo Group's youth gang kept him pleasantly occupied with yakuza wars, mahjong and assassinations... Until the day he stumbled upon a strange drug called Wild Adapter that produces bizarre side-effects—including death. Forever changed, Kubota becomes entangled with a drifter named Minoru Tokito, and the two form an unlikely companionship that draws them deeper into the mystery of Wild Adapter...

The story revolves around a girl named Yuuka, who encounters a being from the depths of the Earth named Chii-chan (a pun of chiteijin, the Japanese word for underground-dweller), and an alien named Ucchan (a pun of uchuujin or alien). The story follows their heartwarming and chaotic everyday lives together.