In the near future, humanity has taken its first steps towards journeying into the far reaches of the galaxy. Upon doing so they discover a huge race of insectoid aliens known as "Space Monsters." These aliens seem dedicated to the eradication of mankind as they near closer and closer to discovering Earth. In response, humanity develops giant fighting robots piloted by hand-picked youth from around the world. Shortly after the discovery of the aliens, Noriko Takaya, the daughter of a famous deceased space captain, enters a training school despite her questionable talents as a pilot. There, she meets her polar opposite, the beautiful and talented Kazumi Amano, and is unexpectedly made to work together with her as they attempt to overcome the trauma of war as well as their own emotions.

Noriko Takaya's dream is to become a space pilot like her father, who died when she was young after an attack by alien forces in deep space. After entering Okinawa Girls Space Pilot High School, she must persuade everyone, especially herself, that she can fulfill her goal and become an accomplished pilot despite being just an ordinary girl.

This double feature comprises of "Gunbuster" and "Diebuster" (aka "Gunbuster 2") condensed into a single theatrical release told in two parts with a musical intermission in between. The 95-minute "Aim for the Top! Gunbuster" movie is a compilation of the original 6-episode Gunbuster OVA, where man first meets the insect aliens and builds fighting robots and huge battleships to combat them. Takaya Noriko and Amano Kazumi lead the fight, doing massive damage to the insect's world. The 100-minute "Aim for the Top 2! Diebuster" movie completes the series, with country girl Nono leading the "Topless" fighters to protect Earth from the invading insects.