Team Dai-Gurren are now on their way to Beastmen's capital city, Teppelin but there's a vast ocean in their way. The only way for them to get across is for the Dai-Gurren to be modified, so while they wait everyone goes to chill out at the beach. Once preparations are complete, the Great Gurren Brigade begins their cruise, but there's an ambush waiting for them.

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.