Most of his life is a mystery. Researchers believe his real name could be Yasufe. Yasufe impressed Oda Nobunga, a powerful daimyo of late 16th century Japan, with his size, power, and understanding of Japanese. Nobunga insisted that he stay (after he reportedly demanded that Yasufe's body be scrubbed because Nobunga thought his black skin was painted on.).
Yasufe became close to the Nobunga clan. When Oda Nobunga was betrayed and killed by Akechi Mitsuhide, Yasufe tried to protect Nobunga's son. Unfortunately they were also ambushed.
This is where Yasufe's trail runs cold. After the defeat, he was returned to the Jesuits. After that, nobody knows what happened to him. Perhaps he was waylaid by vengeful kami? You should finish his story in the most amazing way possible.