They strike without warning and instantly plunge the world into terror. The Great General of Darkness leads the underground Mycenae Empire in a bid to conquer Earth. The Mazinger Army falls before the seven generals under him, each of them leading an army of superior Warrior Beasts. Meanwhile, Archduke Gorgon is relentlessly pursuing Koji Kabuto, trying to eliminate him before he can reach Mazinkaiser. But a red light in the sky over Mt. Fuji portends the greatest battle in history!
 
(Source: Discotek)

In one of their epic battles, the Mazinger Team suffers a crushing defeat at the hands of Dr. Hell and his minions after Mazinger Z is stolen and its pilot, the legendary Kouji Kabuto, is rendered missing in action. Just when Dr. Hell's second-in-command Baron Ashura uses Mazinger Z against our heroes, Kouji makes a surprise return in Mazinkaiser - an all-new Mazinger with heavier armor and deadlier attacks.
 
(Source: Anime News Network)

Kouji and his friends have defeated Dr. Hell and are now enjoying a break, but suddenly a strange prophet appears and warns everyone of an oncoming danger, mechanical beasts never seen before start appearing all around the world wrecking havoc. Its up to Kouji and his Mazinger Z to stand up to this threat but it seems he is vastly outnumber and outmatched. 
This film served as an alternative link between the Mazinger Z TV series and the Great Mazinger TV series. It basically introduces Great Mazinger to the audience, as well as his enemies from the Mikene Empire.

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