I haven't seen the movie yet, but I suspect that it does not really convey what is happening here.
The best way to win an award in an international movie festival is to pick a non-western culture and point out unfairness there :-p
The director himself admits that he wants to convey his experience in Japan; what an adult experiences and perceives are not the same as what a child does.
I have a mixed race, dark-skinned nephew who is well likes and popular in his school; but that does not mean that all kids are in the same boat.
Having been a volunteer working with foreign students for 10 years, I can say that the picture here is much more fuzzy.