As Simon arrives in prison, he unexpectedly meets Viral, who comments on how far he has fallen. Meanwhile, the truth about Rossiu's emergency plan and the consequences for those left behind on Earth are revealed.

One year earlier, Yoko starts working as a schoolteacher on an island until she learns of the situation at Teppelin and returns to break Simon free. Once again reunited, Simon and the members of Team Dai-Gurren launch themselves into space to protect the Arc-Gurren from the enemy forces, now accompanied by Viral as co-pilot of the Gurren-Lagann.

To soothe the public opinion, Rossiu overthrows Simon and puts him under arrest. But when the Anti-Spirals launch a large-scale attack on Kamina City, he is left with no option but to let Simon engage the enemy using the Gurren-Lagann, not before resorting to extremes to put him under his control.

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.

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

A recap of the story's events, as of episode 15.

Trying to do her part in Team Dai-Gurren, Nia decides to become a cook, but just before the crew have a taste of her dishes, Cytomander, the fourth member of the Divine Generals, launches an aerial attack on the Dai-Gurren. Simon leads the counter-attack on the Gurren-Lagann, this time accompanied by Yoko, who replaces a sick Rossiu.

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.

The last of the Divine Generals fall, and the city of Teppelin collapses, revealing a Gunman of gigantic proportions. Simon and Nia struggle to pass through it in order to confront her father, the Spiral King himself.

On their way to Teppelin, the Beastmen's capital city, Team Dai-Gurren stumbles upon a vast ocean and must wait for modifications on the Dai-Gurren to be completed before crossing it. While the rest of the group play at the beach, Yoko starts to feel uneasy about Nia and all the attention she gets from them. After preparations are complete, Team Dai-Gurren begins their sea cruise, oblivious to the fact that an ambush is underway by Adiane and Viral.

Team Dai-Gurren falls into a trap set by the third member of the Four Divine Generals, Guame. The Team is taken captive and stored underground to await execution. While digging an escape path, Simon finally understands Kamina's last words to him and after having a discussion with Guame, Nia finds out the reason why she was thrown away.

Having been temporarily spared by Adiane, another of the Four Divine Generals, Team Dai-Gurren uses the reprieve to reassess their situation. Nia learns of Kamina's significance in Simon's erratic behavior and offers him some stinging, yet honest advice, which draws the ire of an untrusting Yoko. With tension building within the Team, the crew scrambles to stand by Nia's side when Adiane returns to complete her stalled attack.

Thymilph, one of the Four Divine Generals of the mysterious Spiral King, arrives to support Viral's Enki, with the massive mobile Gunmen fortress, the Dai-Ganzan. Kamina and Simon pilot the Gurren-Lagann against seemingly overwhelming odds.

Team Dai-Gurren is still mourning on Kamina's death. Simon notices a Gunman throw a capsule into a deep valley. He inspects it and is able to open it, and inside is a human girl named Nia, but their introduction is cut short when an enemy Gunman appears.

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.

Team Gurren must work together with the eccentric Black Syblings to take down a Beastman foe on empty stomachs.