Devilman: The Birth

Akira Fudou leads the life of a typical high school student. After a chance encounter with school bullies, he is rescued by his childhood friend Ryou Asuka. Ryou and Akira catch up over the course of an afternoon that ends with them crashing a party at a nightclub. Initially uncomfortable with the environment, Akira is shocked when violence provokes some of the club's partygoers to transform into demonic monsters. He and Ryou are only saved from the encounter thanks to the intervention of a great demon known as Amon. Amon possesses Akira, and the two together form the powerful Devilman⁠—a being that, due to the influence of Akira's strong empathy for his fellow man, is resolved to keep the human race safe from the threats of demonkind.

(Source: MAL)