Simon is a driller.  He lives in a subterranean cavern and his job is to drill new tunnels to expand the living area of his clan.  He's quite good at making new tunnels, one of the fastest drillers the tribe has, and one day he discovers a strange spiral shaped object buried deep below the surface as well as a metal face the size of a man.  Simon's friend, Kamina, names the face Lagann and when a huge Gunman (mecha unit) crashes into Simon's cavern, it's Kamina who realizes that Lagann is a Gunman too and that the strange drill shaped object is its key.
 
Practically forcing Simon into Lagann, Kamina and a boisterous red-head named Yoko who followed the Gunman from the surface, manage to defeat the invading monster.  Discovering that there is a surface world, Kamina and Simon leave their village to explore the great outdoors.  Yoko fills them in quickly about the realities of life on the outside:  The Gunman are piloted by Beastmen, animal-like creatures that want to exterminate all humans, which is why most of the population has disappeared underground.

Gunman attack Yoko's above ground village every day.  Kamina, filled with energy and a ridiculous fighting spirit, manages to capture a Gunman during the next attack, which he labels Gurren.  With two mecha on their side, the trio also discovers where the Beastmen base is supposed to be located and take off to put an end to the attacks once and for all.

Along the way they start to gather recruits.  When other humans hear that Kamina fights in a captured Gunman, others start to take the Beastmen's weapons.  Soon there is a small army tagging along.  That doesn't mean that there are no casualties however, and when Kamina unexpectedly dies in battle, Simon is deeply affected.  Even the discovery of a strange girl locked inside a metal box that a Beastman was discarding is enough to shake Simon out of his funk.

This Set:

Things aren't that great at the start of this set.  With Kamina dead and Simon in a deep depression team Lagann doesn't have a leader.  To make things worse, one of the Four Generals attacks and the group has a hard time fending her off.

Then there is the mystery of Nia.  Just who is this strange girl?  It's soon revealed that she's none other than the daughter of the Spiral King, the person who created the Beastmen and who started the war against humanity.  She seems nice and gentle, but most of the humans don't trust her, even though the General who is attacking wants to kill her.

As things progress the brave band of fighters gets closer and closer to the Beastmen's capital, Teppelin.  The closer they get the more resistance they meet and once they see the secret that Teppelin possesses it's not clear if they'll ever be able to win.

The one thing I really like about this show is that it moves at a fast pace.  As where some shows would take seasons to get to the enemy capital, Gurren Lagann does it in a little over a dozen episodes.  Things happen in this program too; main characters die, enemies that seem destined to plague the group forever are dispatched and Team Dai-Gurren achieves the goals they set out to achieve.  That's really great.  After watching countless anime that are enjoyable but where nothing much happens to advance the plot, it's nice to see a show that speeds along at a good clip.
 
Another great aspect of this show is that it's laugh-out-loud funny.  There aren't too man mecha shows that play up the laughs but Gurren Lagann is one of them and it works wonderfully.  The show is outrageous and so over the top that it's impossible not to laugh.  The main comic character is Kamina who gung-ho to the point of being absurd.  He doesn't let logic (or reality) enter into his plans, his fighting spirit will show him the way, or so he hopes.  Typical of his thinking is the advice he gives to Simon when the driller hesitates to pilot Lagann:  "Reject common sense to make the impossible possible!  ... Listen Simon, don't believe in yourself.  Believe in ME!  Believe in the Kamina who believes in you!"

Final Thoughts:
 
This second set is just as entertaining as the first, and that's saying something.  This show has all the action and excitement of a mecha show to boot.  Filled with hilarious situations and some well choreographed battles this show is a 'must-buy.'  Highly Recommended.