Well I guess it really depend on if the characters race is a key aspect of the story or just a product of the setting.
I've never heard of the movie or book you mentioned but it sounds to me like you're saying the source material is Japanese so the main character should be Japanese.
By that logic you could just as easily say the source material is Japanese so it should be filmed in japan and have a Japanese director and the dialogue should be Japanese. saying all that just seems silly though.
At what point are you just saying go home tom cruise you're not the right race for this movie.
I've never heard of the movie or book you mentioned but it sounds to me like you're saying the source material is Japanese so the main character should be Japanese.
By that logic you could just as easily say the source material is Japanese so it should be filmed in japan and have a Japanese director and the dialogue should be Japanese. saying all that just seems silly though.
At what point are you just saying go home tom cruise you're not the right race for this movie.