Joe Shimamura and the cyborgs built by Black Ghost follow a trail of demon attacks to Tokyo, where Akira Fudo is already fighting the same creatures as Devilman. Each side takes the other for the enemy first. Behind both of them the Black Ghost scientist Dr. Adams is fielding a new line of cyborgs while the demons spread through the city, and Dr. Gilmore's team has to choose between trading blows with Devilman and turning on the two threats together. Three OVA episodes cross Shotaro Ishinomori's cast with Go Nagai's.