Deadman Wonderland: The Red Knife Wielder (2011)

Before Senji Kiyomasa was a prisoner at Deadman Wonderland, he was a police officer, using his Branches of Sin powers to put a stop to criminals that stood in his way. After helping an orphan escape the clutches of a notorious local gang called Goreless Peace, Senji finds himself courted by Keigo, the very mastermind behind the violence. But little does he know that his refusal to join forces with evil will have dire consequences...