OP: "Active Heart" 「アクティブ・ハート」
ED: "Try Again"「トライ Again」
The OVA details the story of Noriko Takaya, the daughter of famous space captain Yuzo Takaya, who died in the Luxion disaster of 2015. The story begins in 2021, with Noriko attending a school for aspiring space pilots and Earth threatened by an incoming invasion of Space Monsters. A new coach arrives, sees potential in Noriko, and chooses her to be a pilot in the Gunbuster project, despite her lack of piloting ability. Noriko and her senior, Kazumi Amano, board the Exelion and train to become the pilots of the first two Buster Machines. Upon entering space, it is made apparent that, every time they enter near-lightspeed travel, Time Dilation occurs, sending them into the future. As the series progresses, they continue the fight against the space monsters while the lives they knew on Earth slowly slip away.
- Gunbuster is Hideaki Anno's directorial debut.
- Gunbuster shares many similarities with Hideaki Anno's later work Neon Genesis Evangelion.
- Most of the characters in Gunbuster are named after real people. For example, the lead, Noriko Takaya, is named after her voice actress.
- The series is named after two earlier works which inspired its creation: a tennis manga titled Aim for the Ace! and the film Top Gun.
- A series of shorts titled Gunbuster Science Lessons was created to explain the science-fiction of various aspects of Gunbuster.
- Hideaki Anno supposedly decided to work on Gunbuster after he was given the script and was "moved to tears by it".