In a faraway future, mankind lives underground in caves, unknowing of a world above. In the small village of Jiha, Simon discovers a strange object during an excavation. Kamina, befriends Simon and forms the Gurren Brigade, to escape the village and break through the ceiling of the cave to reach the surface. When disaster strikes from the world above and the entire village is in jeopardy, it's up to Simon, Kamina, a girl named Yoko, and the small yet sturdy robot, Lagann, to save the day. The new friends journey to the world above and find that the surface is a harsh battlefield, and it's up to them to fight back against the rampaging Beastmen to turn the tide in the humans' favor!