Yet that total number of foreign nationals makes up less than 2 percent of Japan’s population of 127 million, a lower proportion than in South Korea, for example, where foreigners make up about 3.4 percent of the population. The share is much higher in the United States, at 14 percent, and it is close to 40 percent in Hong Kong, according to data from the United Nations Department of Economic and Social Affairs.

Obtaining Japanese citizenship is extremely difficult. Since 1952, just over 550,000 people have managed to naturalize as Japanese citizens, most of them ethnic Koreans whose families have lived in Japan for several generations since the colonial occupation of Korea.