My understanding is that there were very few immigrants so immigration was not a political issue. Immigration has started to increase and tourism has boomed so those issues are also beginning to register in political campaigning.

I think it really depends on where you are. I visited Japan early last year and encountered a decent amount of foreigners when I went to the Snow Festival or when I was in Tokyo. But when I was visiting friends in Fukuoka I don't really remember seeing foreigners, and someone in an elevator seemed kind of shocked to see my wife and me. If you don't want to see foreigners, you need to stay away from Tokyo and visit the many, many other interesting places in Japan.

As someone who lived on a military base in Japan when I was a kid, the country does feel like it's changing in places. But other places that are more out of the way still feel like "home", almost unchanged from that time a couple decades ago. (sometimes literally: I visited the area around that base last year and found billboards that were exactly the same as a couple decades ago)