Kouji and his companions have conquered Dr. Hell and are now relaxing, but a weird prophet emerges and warns everyone of an impending peril, and mechanical animals never seen before begin to appear all across the planet, wreaking devastation. It is left to Kouji and his Mazinger Z to deal with this menace, but he appears to be massively outnumbered and outmatched. This film serves as a bridge between the Mazinger Z and Great Mazinger television series. It simply introduces the audience to Great Mazinger and his opponents from the Mikene Empire.