Riki-Oh 2: Child of Destruction.

Riki finds himself in the town of Misaki, dotted with illegal nuclear power plants and run by a religious fanatic military organization called "God's Judgment." He is taken prisoner and made to fight in gladiatorial matches in a sprawling arena. He finds his brother, whose special powers have given him the name of "Savior," but his reunion with his resentful sibling turns sour rather quickly.