Episode 1

In Giha village, an underground town, Simon and Kamina live mundane lives with the constant threat of earthquakes. During an attempt to escape to the surface - something almost unheard of - Kamina and Simon bear witness to a monstrous Gunman, as it crashes through the ceiling into the middle of their subterranean home. Together with the Gunman's pursuer, a girl from the neighbouring village, Yoko, the two young men find the key - a small Gunman buried deep in the ground, named Lagann by Kamina - to both defeating the massive intruder and leaving Giha Village.

Prologue
An unknown battleship soars through space. On the bridge, figures move about, at their repective battle stations. At one station, the person detects a large group of ships, identified as the enemy, heading toward them. The commander sighs, then looks up at the stars and says "Are all the lights in the heaven our enemy?" [white light fills the screen]

Story
Simon, a 14- year- old boy who lives in the underground village of Giha, is doing his job of digging to expand the village when he uncovers a small drill that glows at his touch. He leaves his hole and comes out to the village, where a few girls see him and mock him.

He walks away with his head down and bumps into Kamina, a person he calls Aniki or bro, even though they have no true relation. He grabs Simon and forces him to join him in an attempt to head to the surface. They ride some mole-pigs to try and break through the roof but are foiled by the village leader, who says Kamina is a liar about the surface, just like Kamina's father. Kamina claims he and his father went to the surface earlier, but no one believes him so he is thrown in jail, and Simon is sent back to dig more. While he is digging he finds another discovery, a face which is later revealed to be Lagann. He quickly rushed to break Kamina out of jail. He says he will take Kamina to the face he found, but the village leader finds them again. But before he can punish them, a gigantic robot breaks through the roof, and with it a girl who was battling the mecha.

They try to fight the Mecha unarmed, but are no match to it, so Simon realizes that if he brings them to the face and maybe it could help them. Simon brings Kamina and the girl to the face, and the drill over his neck starts glowing more, and he learns that it can activate it.

He activates the mini-mech, and confront the larger "Gunmen" as they are called. Kamina says that "Heaven may forgive you, but this Lagann will never" which gave the mini-gunmen the name Lagann. Using the drills on Lagann they defeat the enemy, and break through to the surface, and the girl tells them her name is Yoko.

The sight amazed Simon and Kamina but Kamina and Yoko soon learn they are falling. Simon closes the hatch but they crash into the ground,sending everyone out. Simon comically lands on Yoko, she responds with a smile, however Yoko's face suddenly widens with shock as she pulls him closer to reveal two more Gunmen behind them.

Major Events

 * Introduction of the main characters
 * Introduction of Gunmen

Eyecatchers
Post Commercial: Simon appears in a tunnel, wearing his tunneling clothes as he looks at the screen, his drill pointing forward.

After Commercial: The Village chief looks down menacingly while the Gunmen appears in the background with light shining down fromthe whole in the city.

Trivia

 * The first Gunmen is never named.
 * At the beginning of the episode, right after the intro there is a clip of Simon and 2 unnamed people on the Cathedral Terra with the Gurren Brigade in the background. (One man resembling Boota during his transformation into a human). It is possible that this is the actual Cathedral Terra, as there is Gurren Laggan flag, and Kamina's famous phrase "Just who the hell do you think I am?" is shout by the commander.
 * The writers later said that the beginning shows what might have happened if Simon had ignored the Anti-Spiral's final words and caused the Spiral Nemisis. As it turned out, this answer came from a theroy presented by fans to the creators.