I think one of the biggest scares in Japan is that there are people more loyal to government in Pyonyang, North Korea than the current government in Japan. These people (jochongnyon) were rather separate and went to North Korean schools and had ongoing relations with North Korea through their polical party and association.
We have heard of the assassination of President Park's wife by a Japanese-Korean who was actually a North Korean spy. We also hear on the News constantly about tyring to get the families of the 9 Japanese who were abducted by North Koreans in Japan and sent to N. Korea back to Japan.
I think the number of people affiliated with the Communist political party in Japan is growing as their children get married and have children and grow up.
The best solution to the problem for Japan is to improve the quality of life for the Japanese by increasing job opportunities and pay wages. Right now, most Japanese live at a very low level which I think puts them in a vicious circle where some people will continue to feel disgruntled and to have sympathetic feelings toward the Pyongyang government which has a record of terror and sabotage.
I think the world is giving Japan enough in sales revenue of products for them to be able to improve the standard of living of their citizens. Increased wages could also be achieved through long-term loans.
If they're trying to marginalize everyone in fear of immigration from abroad. There's no need to worry, because rent will only increase as wages do.