Hong Kong (CNN)When feudal Japan's most powerful warlord Nobunaga Oda met Yasuke, a black slave-turned-retainer, in 1581, he believed the man was a god.
African samurai: The enduring legacy of a black warrior in feudal Japan
Oda had never seen an African before. And like the locals in Japan's then-capital of Kyoto, he was awed by Yasuke's height, build and skin tone, according to Thomas Lockley, the author of "African Samurai: The True Story of Yasuke, a Legendary Black Warrior in Feudal Japan."
"When Yasuke got to Kyoto (with Jesuit missionaries), there was a massive riot. People wanted to see him and be in his presence," says Lockley, who spent nine years researching and writing the book, which was published last month.
Oda believed Yasuke to be either a guardian demon or "Daikokuten," a god of prosperity usually represented by black statues in temples. He tried to rub the pigment from Yasuke's skin, believing it was black ink. Once convinced Yasuke was real, he immediately threw a feast in his honor, says Lockley.
In an era racked by political espionage, merciless assassinations and ninja attacks, Yasuke was seen as an asset. Nobunaga soon made him a samurai -- even providing him with his own servant, house and stipend, according to Jesuit records.
Today, Yasuke's legacy as the world's first African samurai is well known in Japan, spawning everything from prize-winning children's books to a manga series titled "Afro Samurai."
And his legacy continues to spread worldwide.
Earlier this month, "Black Panther" star Chadwick Boseman announced he would play Yasuke in a Hollywood movie scripted by "Narcos" co-creator Doug Miro.
Lockley says his story has reemerged just as homogenous Japan reexamines the concept of multiculturalism in the run-up to the 2020 Tokyo Olympics.
Yasuke's origins remain a mystery as historical sources are scant. While some researchers believe he was from Mozambique, others suggest Sudan.
Lockley suspects that Yasuke was abducted from his family as a child by Arab or Indian slave traders and trafficked through Arab countries and across the Indian Ocean. He likely worked as a slave and trained as a child soldier who fought in Gujarat and Goa in India, before being hired as a valet by Jesuit missionaries from Portugal.