It is common in isekais anime for the protagonist to die and be reincarnated in ANOTHER different WORLD where everyone is white and Asian. Generally the protagonist is a Japanese person who was reincarnated in a fantasy world based on European mythologies in which he starts to live with elves, fairies, elves, etc.
So my question is: how likely is it that someone would complain about a story that takes place in another world where all the characters are black? Would a fantasy story based on African mythology be subject to complaints?
Based on the title, I was originally going to say “Simpsons did it!” as they acknowledge they’re yellow, though Karl, Apu, and some others are neither white nor yellow.
Would anyone be mad at a story like you mention in your story? Of course they would! See the backlash to something like The Woman King (2022). If you go by the time period it was set in, many would not consider the Portuguese white, and the rest of the cast is black. Even something like Black Panther that did have multiple races in it got complaints about how people “couldn’t relate to the characters.”
Or think about when people were mad at the female Ghostbusters movie before it even came out.
From a less potentially bigoted position, you have another issue. If you isekai into another race, you need to be mindful of how you write it. For example, if you have a white person reawaken in a black person’s body, now what? You’re either going to be writing a black person who now acts white, or a white personality who now tries to act black to fit in. I think a team of multiethnic writers could lend good perspective to this, but it’s a lot of landmines to avoid if you did it solo.
It could end up being very good if the story shows how much we both have in common and addresses our misunderstandings, but a lot can go wrong.
I’m sure you can think of a male author who writes very terrible female characters, even though his male characters are great. With race, I feel your touching something even more sensitive and personal.