WIKIPEDIA:

“ Gunbuster, known in Japan as is a six episode anime OVA series created by Gainax in 1988. It was the directorial debut of Hideaki Anno, best known as the director of Neon Genesis Evangelion. The title is a combination of the titles of classic tennis anime Aim for the Ace!, whose plot inspired Gunbusters, and the 1986 film Top Gun. To celebrate Gainax's 20th anniversary in 2004, an official sequel to Gunbuster, Diebuster (or Gunbuster 2), was released as an OVA. The sequel features new characters and mecha, but retains the format and many of the concepts of the original series.

Plot
In the very near future, a race of huge, insectoid aliens is discovered traveling the galaxy. These aliens, which are known as the Uchuu Kaijuu, or Space Monsters (Note: This name is what they are referred to throughout the series, although the Super Robot Wars games names them the "STMC" or "Space Terrible Monster Crowd"), seem dedicated to the eradication of the human species as the latter takes its first steps away from the solar system, and they are getting closer and closer to Earth. Humanity has responded by developing space-going battleships and giant fighting robots. These complex robots—RX-7 Machine [......] ”

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