According to Histoire Ecclesiastique Des Isles Et Royaumes Du Japon, written by François Solier of the Society of Jesus in 1627, Yasuke was a Muslim from Mozambique.
Solier’s account may however have been an assumption, as it was written so long after the event and there is no surviving contemporary account that corroborates it. Therefore, although there is no evidence, it is also possible that he also came from Portugal, Angola or Ethiopia, and he could conceivably originally have been an African mercenary in the employ of an Indian sovereign, of which there were many at this time.
A 2013 investigation by the light entertainment television program Discovery of the World’s Mysteries suggested that Yasuke was a Makua named Yasufe. However, this was a highly journalistic investigation; the program provided little proof for their conclusions. He may otherwise have been a member of the Yao people, who were just coming in to contact with the Portuguese at this time, which might account for his name, ‘Yao’ added to the common Japanese male name suffix of ‘suke.’
Yasuke arrived in Japan in 1579 as the servant of the Italian Jesuit Alessandro Valignano, who had been appointed the Visitor (inspector) of the Jesuit missions in the Indies (meaning East Africa, Southand East Asia). He accompanied Valignano when the latter came to the capital area in March 1581 and caused something of a sensation. In one event, several people were crushed to death while clamoring to get a look at him
The Jesuits feared their church would be flattened in the stampede, but they managed to avert disaster. The warlord Nobunaga, famous for his attempts to unify Japan, heard the noise from the temple where he was staying and expressed a desire to see him. Suspecting the dark color of his skin to be black ink, Nobunaga had him strip from the waist up and made him scrub his skin.
These events are recorded in a 1581 letter of the Jesuit Luis Frois to Lorenço Mexia, and in the 1582 Annual Report of the Jesuit Mission in Japan, also by Frois. These were published in ‘Cartas que os padres e irmãos da Companhia de Jesus escreverão dos reynos de Japão e China II’, normally known simply as ‘Cartas,’ in 1598. Satisfied that he was, in fact, black, Nobunaga seems to have taken a shine to him. At some point following this, although when is not clear, he was either given (Japanese accounts indicate him presented to Nobunaga, although European accounts do not mention this) or allowed to enter Nobunaga’s service.