Mao Dante

Mao Dante is a manga and anime series created by Go Nagai. The protagonist, Ryo Utsugi, is drawn to the Himalayan mountains where he frees the demon Mao Dante and, in reward for his unwilling service, is eaten. Ryo then reawakens to find that he has merged with the massive body of Mao Dante, and while he is in control of the demon he is still compelled to destroy humanity. Ryo later learns that modern humanity are actually all aspects of a being known as God, and that Earth's true humanity was almost wiped out by God thousands of years ago. Those few humans that remained became demons in order to survive God's wrath. Ryo is then compelled by the demons that remain to wage war against God and reclaim Earth for the original Humans.

Lamia
Lamia is one of the four demon horsemen summoned by God to lure Mao Dante out of hiding. As opposed to her more violent cohorts, she kills by sucking the life force out of her targets. Her personal ploy to lure out Dante involved the creation of Lamia's Labyrinth, an alternate dimension where youth were lured by their lust, greed, and vanity. Once there they were impregnated with her demonic spider babies, which would overrun the country when born. Dante was indeed lured in when Saori was taken, but his rage was great enough to kill all four of the horsemen, Lamia included.

Medusa
Medusa was the lover of Dante in the prehistory city of Sodom. She escaped the city along with Dante, and recieved the demonic power to turn living things to stone. In modern times she has taken the alias of Saeko Kodai, a model. She told Ryo of his past and stood with him in the fight against God, but died in the process of waking the demon lord Satan.

When Ryou travels to hell in Devilman Lady he briefly travels through his own past, and witnesses Medusa turning into a monster after being attacked by God.

Ura
Ura was one of the humans who became demons in God's first attack upon the Earth. She, along with her fellow demons, lead the Satanists until Mao Dante could be revived. She was killed by God's dragon in the apocalypse.