@Amir the difference is that Ieyasu Tokugawa due to the services provided gave the tittle of Samurai to William Adams. As far as I know, that is a real historical event. Yasuke, on another hand never had such tittle, and the Japanese take seriously those records on a cultural level.

The thing here is that they did bad research, decided to take the word of a con-artist, Thomas Lockey, that attempted to adapt his romance into something factual (Yasuke being a Samurai), when he was a retainer at best, and a slave/oddity to the Japanese at worst, and pass the “Yasuke, the Samurai” as a samurai, and signal virtue anyone that would bring up the facts, even to the point that they would say westerners were faking comments in Japanese to complain about the game, when the Japanese were voicing their concerns to the fact that if they want to make a game with historically accurate depictions, then they should learn more about their culture, and Ubisoft dismissed that. It came into a point where wiki articles were being edited and Japanese history being compromised online to fit such agenda. The Japanese government eventually looked up the issue, accused the western people of whitewashing their culture, and cultural appropriation, and the guy who wrote the Yasuke novel, Thomas Lockey, is being investigating for deliberately attempting to push his writings as historical academic papers, and incentivising third parties to do so as well, when they are in fact, fiction.

If the game was in a fictional setting, and they would be clear about it, the Japanese wouldn’t mind. Pretty much like Nioh, that is a fantasy game based on Japanese lore, Team Ninja never stated that Nioh was based on historical events, unlike Ubisoft been pushing with Assassin’s Creed’s Yasuke portrayal to appeal to a very specific demographic.