 As soon as the world's population reaches one million people, an alien race called the Anti-Spirals emerges and uses Nia to announce the Moon's collision with Earth, which will wipe out all life on the planet and prevent them from evolving to such an extent that they will risk destroying the universe in a cataclysmic event called the Spiral Nemesis.With guidance from Lordgenome resurrected as a bio-computer, who was once part of an intergalactic group of warriors who fought the Anti-Spirals and had hidden mankind underground to protect them from the Anti-Spirals, and with help from Viral, an old enemy of Simon who pilots Gurren, Simon, Gurren Lagann and Team Dai-Gurren prevent the Moon's collision, revealing it to be Lordgenome's flagship that was reprogrammed by the Anti-Spirals.Using it, they retrieve the real Moon from the pocket dimension where the Anti-Spirals had hidden it and go to the Anti-Spiral homeworld.