Living underground in Giha Village, Simon and Kamina dream of a life on the surface. When their home is invaded from above, it is up to them to activate the mysterious mecha Lagann and save their village.

Now that they've made it to the surface, Simon and Kamina must join together with Yoko and her village to defeat the Beastmen pursuing them.

Having temporarily stalled Viral and Thymilph in the last skirmish, the Team Gurren and their newly arrived allies join forces as "Team Dai-Gurren" and launch a decisive strike against the regrouping Gunmen force.

Nia true identity is revealed, as she flaunts her authority to get rid of another one of the Four Divine Generals, Adiane. The members of the Great Gurren Brigade are now suspicious of Nia and her true intentions, but she is only concerned about the depressed Simon. Adiane later returns to finish them all off, with Lordgenome's blessing.

At last, Team Dai-Gurren arrives at the outskirts of Teppelin, but before aiming to the city, they must face a combined full-scale attack of Cytomander and Guame's forces.

Guided by Simon and Nia's feelings for each other, Team Dai-Gurren break through dimensions in search for the Anti-Spirals' homeworld. But after falling into the enemy's trap, they end up losing some of their most precious members, due to its vicious offensive.