Kamina and Simon must work together to defeat a dangerous new Beastman threat.

Continuing to the Gunmen rallying point, Team Gurren finds themselves on a strange hot springs getaway.

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.

During the following seven years, a new civilization rises and prospers under Simon's leadership. However, these peaceful times come to end when the threat mentioned in Lordgenome's last words starts to reveal itself.

The members of Team Dai-Gurren make their preparations for the imminent war against the Anti-Spirals, but Rossiu is missing. However, when Kinon tells Simon about what he really intends to do, both start to look desperately for him.