There are some people who are unhappy about immigrants, and also about Chinese citizens buying large amounts of land in Hokkaido. But this is a really small group of people.
The problem is that there are a few politicians who rely on the block vote of these people, and the nationalists. So, they occasionally go on air saying something anti-immigrant. But the mainstream media usually jump on them and get them to apologise.
Last year, a group of people hosted a "Japanese Only" banner at one of the league soccer games. The home team apologised, and played their next game without spectators, to compensate.
Over the twelve years I stayed here, I have noted that the demonstrations - and trucks with loud songs - by the nationalists have been on the decrease. Most anti-immigrant demos you see in Ueno are paid performances by the gangsters.
Overall, there is nobody who call immigrants "Foreign Trash" (like they do in Singapore). There are some cases where foreigners cannot rent apartments or enter clubs, but these are on the decrease.