Ryo Asuka

The best friend of Akira Fudo, the main character of Nagai Go's classical horror manga Devilman.

As Akira is the strength, Ryo is the brain. His father discovered the existence of demons in our world and decided to fight them. He asked his friend Akira for help. Ryo knew that to be able to beat a demon, one had to become a demon. He and Akira went through a ritual to fuse with demons, but in the end, only Akira was able to do so and became Devilman, leaving Ryo remain as a normal human.