Driven to revenge by the death of his family, Zōng-Wǔ turned evil and joined the Nazis as a German army officer even though he is Chinese. He had the chance to kill Adolf Hitler, but didn't because he felt Hitler is too pitiful a prey for him to kill.
He later renounces his evil ways and becomes a monk. His facial features are similar to that of Raoh and Kaioh, implying he maybe a blood relative.(Source: Wikipedia)