Top o Nerae! 2: Diebuster (トップをねらえ！２：ダイバスター) is a 2004 sequel to Gunbuster which was produced for Gainax's 20th anniversary. It was published by Gainax. It was not, however, directed by Hideaki Anno, but by Kazuya Tsurumaki, the director of FLCL and co-director of the Evangelion rebuilds. The series was made by the same team that created FLCL and shares many similarities to it in animation and style, even to the point that it's more similar to FLCL than it is to Gunbuster.
OP: "Groovin' Magic"「Groovin' Magic」
ED: "Hoshikuzu Namida"「星屑涙」
WARNING: CONTAINS SPOILERS FOR GUNBUSTER AND DIEBUSTER Edit
12,000 years after the events of Gunbuster, a robot named Nono (ノノ), who works at a bar on Earth, dreams of becoming a Buster Machine pilot just like her hero, Nono-Riri (ノノリリ). Coincidentally, she ends up right in the middle of a battle between a Buster Machine and a monster from beneath the ground. The machine and the monster fly up into space, with Nono clinging onto the machine, and the pilot, Lal'c, takes her back to The Fraternity. When humanity is once again attacked by Space Monsters, Nono, who was never given a Buster Machine of her own, is revealed to be Buster Machine 7, a gigantic planet-sized mecha which has the power to single-handedly win the battle and save humanity. The series ends with the lights of Noriko Takaya and Kazumi Amano's escape pods as they exit Gunbuster.