Ryou Asuka is the best friend of Akira Fudo, the protagonist of Devilman. Though the two were separated after Akira switched schools, they were reunited when Ryou sought Akira's help to stop the demons which had begun to reappear in the world. In order to better their chances of success, Ryou suggests the two of them fuse themselves to become a devilman—heart of a human, but the body and power of a demon—though only Akira is successful. As Devilman, Akira works with Ryou to fight the increasing onslaught of demons.