Japanese people may not understand segregation or racial discrimination in the USA especially.
Of course African people had been slaves for white people in the history. African people (black persons) had been moved as slaves from Africa for plantations in the south area of the USA.
Recently a black man was killed by a policeman. This matter has repeated many times in the history of the USA, and people have had a lot of demonstration against segregation until now.
But in this time, demonstration has spreaded in wide area of the USA. And some people have violence for shops and loot. Now the situation has become very difficult.