Grendizer: Getter Robo G - Great Mazinger Kessen! Daikaijuu
Japanese title: グレンダイザー・ゲッターロボＧ・グレートマジンガー 決戦！大海獣
Type: Movie
Source: Manga
Episodes: 1
Status: Finished Airing
Aired: Jul 18, 1976
Duration: 31 min
Rating: PG-13 - Teens 13 or older
Studios: Toei Animation
Producers: Dynamic Planning
Genres: Action, Sci-Fi
Themes: Mecha
Demographics: Shounen

A giant sea monster known as "Dragonsaurus" has emerged from out of nowhere, terrorizing the depths of the oceans. Great Mazinger, Grendizer and the Getter Robo G team join forces to combat the new threat. But their task becomes more complicated when Dragonsaurus swallows up Boss Borot and makes its way toward Tokyo.

(Source: ANN)