No particular horse in this race, so I googled “evidence against Yasuke being a samurai”, as I felt that was the more open question to ask.
There are of course various results, too many to share here. But I picked this one, as I liked its conversational tone. And frankly, the Smithsonian feels like a reliable source.
https://www.smithsonianmag.com/history/who-was-yasuke-japans-first-black-samurai-180981416/
So, first and foremost? Yasuke, the man, existed. He himself is
not a myth.
I feel that’s a solid base to start exploring from, yes? Establish we’re not talking about a semi-mythical folk hero or a misinterpretation of historical reports.
It also establishes Yasuke was already a warrior, whether or not he freely accompanied Valignano, because as a Jesuit Missionary, Valignano was forbidden from carrying weaponry.
This makes it plausible he could have been a viable candidate to become a Samurai, as he already knew some form of martial art.
It then cites a 17th Century, contemporaneous account written by one of Nobunaga’s associates that Yasuke was noted for having great physical strength.
Then it establishes that in that century, a Samurai was defined as a warrior in service to a Lord or another Warrior. I take that to mean a
professional warrior, and not say, a member of an ad-hoc militia raised to bolster numbers. Furthermore, he was part of a smaller circle of warriors that accompanied Nobunagas
The Gamer whilst itself not a historical source, does cite Japanese Historian Yu Hirayama as confirming Yasuke’s status as a Samurai. However, I’m struggling to find confirmation that Yu Hirayama isn’t some quack - I’ve been around the conspirasphere long enough to know to check these things. But equally, I can’t find anything to say he definitely is a quack.
But the consensus does seem to be Yasuke was in fact a Samurai. And so any claims to the contrary will need quite considerable citation to back them up. As in, more than “this person on Twitter said he’s not” citations. And unless the poster happens to be a suitably qualified historian of that period of Japanese history, their insistence should be treated very cautiously.
For me though? It seems he is though of as a Samurai - but there is room for doubt due to a general lack of historical documents explicitly confirming or denying.