Team Dai-Gurren managed to take control of the enemy fortress, but is still mourning the death of one of their own, especially Simon. After falling off a cliff, he notices a Gunman throw a capsule into a deep valley. Simon inspects it and finds he is able to open it with the same drill key he uses to pilot Lagann, and inside is a young human girl named Nia, but their introduction is cut short when an enemy Gunman appears.

After the Anti-Spirals' first attack and Nia's astonishing announcement, Simon looks desperately for her, while Rossiu finally completes his secret project.

Die Super-Galaxie Dai Gurren wird im Weltraum von einem mysteriösen Meer angegriffen und droht, zu versinken. Simon und seine Freunde überlegen sich einen Plan, um aus der Falle des Feindes zu entkommen, doch dafür muss das Team ein großes Opfer bringen...