Soukoku no Garou: Hokuto no Ken Rei Gaiden

Rei is a ruthless man who is traveling the world in search of a certain someone... But Rei was not always ruthless an uncompassionate, it's vengeance the one who stripped Rei from his humanity, and he won't be able to become a normal human being until that vengeance is fulfilled. Right now, he can only roam the world as a furious lone wolf, a lone wolf who preys on those who oppose him.