Mazinkaiser (マジンカイザー) is an Japanese anime OVA, consisting of seven episodes, released on Japan in 1999, and based on Mazinger Z, originally from manga artist Go Nagai.
The basic plot is a re-telling of the adventures of Kouji Kabuto, pilot of the mighty Mazinger Z, the first Super Robot of anime, defender of Japan and of the Photon Energy research laboratory. He is joined by another hero, Tetsuya Tsurugi, in his Great Mazinger, along with token girl Sayaka Yumi in her female robot Aphrodite A, and comic-relief Boss and his Boss Borot. They all fight against the evil machines of Dr. Hell and his assistant, the half-man, half-woman servant Baron Ashura. This time around, however, Ashura forms an army of machines powerful enough to able to defeat both Kouji and Tetsuya, and is able to capture Mazinger and do severe damage to Great Mazinger.
While Ashura and Dr. Hell plot the final attack to the Photon Laboratory, Kouji, who is missing after the battle, finds a hidden laboratory of his dead grandfather, Juuzou Kabuto. There he finds a hologram of his grandfather that tells him that the time has come to unleash the most powerful robot ever created: Mazinkaiser, so terribly powerful it can as easily be used as a lethal weapon of evil as it can be for good ("Mazinger Z gives you the power to be God or the Devil, but Mazinkaiser allows you to surpass both!"). Kouji, now piloting Mazinkaiser, arrives just as Ashura is almost on the verge of destroying the Photon lab, and defeats him. Ashura leaves, stunned and hardly believing that a new Mazinger has arrived.Wikipedia