After Akira Fudou fused with the demon Amon to become the being known as Devilman, he has struggled with striking a balance between his human heart and his new violent tendencies. However, as other demons become aware of him and wreak havoc on the lives of those he cares about, Akira has little choice but to fight them tooth and nail. As he fights Jinmen, a turtlelike demon with living human faces embedded in his shell; and Sirene, a fearsome winged demon, Akira must use every scrap of his strength if he is going to stay alive.