The Japanese are known to be very xenophobic but they hide it well with their polite demeanour. Their whole Shinto religion is based on the concept of supposed Japanese racial purity.Northeast Asians are racist when it comes to immigration to their countries.
At first I used to think it was because their countries were overpopulated (remember China had a one child policy and Tokyo metro area is like 38 million people for one city), but since many major economic think tanks have been advising them to open up immigration due to their rapidly aging population (especially Japan) and them hesitating/not accepting this, the only conclusion is that they are racist as f*ck.