After the world ends in the original Devilman story, Akira Fudo descends into hell searching for the soul of Miki, the woman he lost. There he meets Hades, the Emperor of Darkness, who offers a bargain: cross to another Earth, destroy the machine that stands in his way there, Great Mazinger, and Miki will be restored to life. Weighed against the one person he still wants back, the price starts to look payable, and Akira has to decide how far he'll go. This crossover manga sets Devilman against the Mazinger Z and Great Mazinger franchise.