Buraiden Gai

One incredibly tough kid tries to clear his name. He’s no murderer, and he’ll do whatever it takes to prove it…
From Baka-Updates:
The story revolves around Kudo Gai, a mischievous 13 year old all alone in the world. He despises his classmates who live by their free will, although supported by parents, but taking it for granted. Gai soon finds out he is contradicting himself for he is being raised at an orphanage as well,and makes an attempt for independence. His actions lands him in trouble, where he is framed for murder and sent to a place in an unknown location called the ‘human institute’.