Nia is a mysterious young girl found by Simon sleeping in a capsule in the middle of a dump site. She has had no prior contact with humans except her father. She is very curious, pure and innocent, because of a sheltered childhood in a peaceful environment away from all the battles occurring in the outside world, and because she had only recently gained sentience. During her travels with the Dai-Gurren Brigade, she discovers the harsh realities of the world and has a very close relationship with Simon throughout the story.