“When Yasuke was presented to Oda Nobunaga, the Japanese daimyō thought that his skin must have been colored with black ink. Nobunaga had him strip from the waist up and made him scrub his skin.[22] These events are recorded in a 1581 letter of the Jesuit Luís Fróis to Lourenço Mexia, and in the 1582 Annual Report of the Jesuit Mission in Japan, also by Fróis. These were published in Cartas que os padres e irmãos da Companhia de Jesus escreverão dos reynos de Japão e China II (1598), normally known simply as Cartas.[23][24] When Nobunaga realized that the African's skin was indeed black, he took an interest in him.”
Oh sure, it was incredibly unusual but once everyone got used to him being around after a few years, or a generation if he had kids, the novelty would wear off. I just don’t think it matters.
That said, 'historical fictions' are usually much more fiction than historical.