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.

In the year 2314 AD, the world is at peace. Thanks to the sacrifices of Celestial Being and its mobile suit pilots, the people of Earth experience a time of prosperity and unity, enjoying tranquil lives once thought impossible. Celestial Being, an organization once painted as villains by the Earth Sphere Federation, now exists in public perception as a group of heroes, celebrated in film and culture.

When an extraterrestrial threat arrives on Earth, threatening the newly acquired calm stasis, Celestial Being springs back into action. Led by ace pilot Setsuna F. Seiei, the Gundam Meisters of the group battle the hostile alien forces, teaming up with old rivals to protect the human race from certain doom.

[Written by MAL Rewrite]

At the climax of the Eve Wars, on December 24 of the year AC 195, the armies of the World Nation and White Fang met in a ferocious battle. World Nation leader Treize Khushrenada was slain, White Fang leader Zechs Merquise disappeared, and Earth was saved from destruction by the intervention of the five Gundam pilots. Having witnessed the consequences of war and hatred, the people of Earth and the space colonies put aside their differences and together founded a new world government. Under this newly-formed Earth Sphere Unified Nation, a year has passed in peace. The government and the populace have disarmed themselves, and almost every remaining mobile suit has been destroyed. Deciding to follow suit, Gundam pilots Heero Yuy, Duo Maxwell, Trowa Barton, and Quatre Raberba Winner place their mighty mobile suits inside an asteroid and send them on a one-way voyage into the sun. But even as they bid their Gundams farewell, a new conflict is drawing near. 

(Source: AniDB)