After triumphing over Dr. Hell, Kouji and his comrades relish a moment of respite until a mysterious seer forewarns them of a looming peril. Unprecedented mechanical beasts emerge worldwide, wreaking havoc and thrusting Kouji and his Mazinger Z into a daunting battle where they face overwhelming odds. This cinematic tale acts as a narrative bridge between the Mazinger Z and Great Mazinger TV series, unveiling the debut of Great Mazinger and the formidable foes from the Mikene Empire to the viewers.