Baron Ashura attacks Japan with an army of Mechanical Beasts, but is met head on by Kouji Kabuto and Mazinger Z. Ashura's forces manage to get the upper hand, and despite the arrival of Great Mazinger, Boss Borot and Aphrodite A, Mazinger Z is disabled and Kouji hurled to parts unknown. Dr. Hell quickly modifies Mazinger Z into the Ashura Mazinger and launches an attack on the Photon Power Lab. Despite Great being damaged, Tetsuya Tsurugi attempts a valiant defense but is overwhelmed. Before he can be killed by a gloating Ashura, a mystery robot wipes out the entire attacking Mechanical Beast army with one shot. Overpowering Ashura Mazinger easily, the mystery robot begins attacking the Lab and Great!