UFO Robo Grendizer tai Great Mazinger is an anime film that premiered in spring 1976, produced by Toei Animation.

About the production: the film runs about 30 minutes and its current status is "finished".

Its main genres are mecha and sci-fi, with themes such as Super Robot, Crossover and Aliens.

On AniList, UFO Robo Grendizer tai Great Mazinger has an average score of 60%, an average score, and appears on 1,141 users' lists.

Alien invaders take over Great Mazinger who is at the entrance of a museum next to Mazinger Z as symbols of peace. Grendizer fights the evil invaders and Great Mazinger is recovered. When the Vegan empire dispatches a new general to oversee the takeover of Earth, he quickly manages to capture Koji Kabuto and, learning of Great Mazinger through interrogation, quickly commandeers it from a museum where it was kept as a symbol of peace. It is now up to Duke Fleed aboard Grendizer to stop humanity's former defender from becoming its destroyer. (Source: Anime News Network)

Official synopsis from AniList.