Gunbuster, known in Japan as Aim for the Top! Gunbuster (トップをねらえ!, Toppu o Nerae!) is a six-episode anime OVA series created by Gainax in 1988. It was the directorial debut of Hideaki Anno. The title is a combination of the titles of classic tennis anime Aim for the Ace! and hit action drama film Top Gun, whose plot inspired Gunbuster's. 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.
In the very near future, a race of huge, insectoid aliens are 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.