“Is there an army of lawyers ready to sue the schools for violating the students’ “Civil and Human Rights?” - as there would be in the U.S.?”
While Japan has more ‘history’ to account for than the US, and certainly more recent history (as in WW2), they also figure that engaging in the cultural-suicide that the West is undergoing isn’t going to change their past.
So to answer your question: Nope - they have little or no guilt about their past, and so they don’t have the equivalent of a Democrat Party, nor their army of lawyers and judges to destroy their country from within.
U.N. urges Japan to resettle more refugees
https://www.reuters.com/article/us-japan-refugees-idUSKBN1DK0WW
Hope they stay strong.