"Gurren Lagann" is a mecha manga series set in a dystopian future where humanity is forced to live underground due to the oppressive rule of the Spiral King, Lordgenome. The story begins in the subterranean village of Jiha, where a young digger named Simon discovers a small, drill-shaped mecha called Lagann. Alongside his brash and ambitious friend Kamina, Simon uses the Lagann to break through to the surface world, defying the village's oppressive norms. Kamina, driven by a desire to reclaim the surface for humanity, forms the group Team Dai-Gurren, which grows as they encounter other humans and mecha pilots.

The surface world is revealed to be a harsh, barren landscape dominated by Beastmen, genetically engineered soldiers serving Lordgenome. Simon and Kamina, piloting the combined mecha Gurren Lagann, lead a rebellion against the Beastmen, inspiring others to join their cause. After a climactic battle, Kamina sacrifices himself to protect his comrades, leaving Simon to grapple with grief and self-doubt. Despite this loss, Simon matures into a capable leader, continuing the fight against Lordgenome's forces.

The narrative shifts focus as Team Dai-Gurren grows stronger, eventually confronting Lordgenome himself. After a fierce battle, they defeat him, only to discover that his tyranny was an attempt to protect humanity from an even greater threat: the Anti-Spiral, a race determined to prevent the overuse of Spiral Energy, which powers the mecha and threatens universal destruction. Years later, Simon and his allies, now leaders of a thriving human civilization, must face the Anti-Spiral in a final, universe-spanning conflict. The story explores themes of perseverance, hope, and the consequences of unchecked ambition, culminating in a resolution that balances triumph and sacrifice.

Key characters include Simon, whose growth from a timid boy to a resolute leader forms the emotional core of the story; Kamina, whose boldness and charisma inspire those around him; and Yoko Littner, a skilled markswoman who becomes a vital member of Team Dai-Gurren. Other notable figures include Nia, Lordgenome's daughter, who becomes a central figure in the fight against the Anti-Spiral, and Viral, a Beastman who evolves from an adversary to an ally. The series blends intense mecha battles with personal struggles, creating a narrative that balances action and emotional depth.