It is basically about a group of people who are known as parasites who protect the mainland from monsters and they discover about themselves and about their past and where did they come from.
They are totally isolated from the main world and they stay outside of it to protect the main city.
Starting is really really really boring but it gets so good after 12th Episode worth giving a Try but Patience is required.
The Art is not much of a big deal except the way the Mecha is operated looks ecchi but I am surprised that there was not even a single ecchi part in it.
Sound:- Not much of a music guy but the opening was not that great.
Enjoyment:- Forget about it for the first 12 Episodes I literally slept during 2 or 3 episodes and I refreshed myself and continued watching but after the 12th episode, it gets good but you’ll not end up sleeping.
Overall: Worth Giving it a Try, the story is same as Gurren Lagann but this is way boring in the beginning and there might be season 2 for this.