Gundriver

Dick lives a quiet life on the frontier with his father and sister, Anna. He dreams of purchasing a Gun Driver, a type of mech piloted by gunslingers. After saving enough money, he is denied a purchase due to racial discrimination. When he returns home, it is attacked by a gang of Gun Driver pilots known as "The Wild Bunch," who leave him with the loss of his left arm. His father donates his own left arm to save Dick’s life. He later joins a mobile brothel named "Jewel Palace," which supports him in seeking revenge and rescuing his sister, Anna.