WHAT IS THE BIGGEST NON-JAPANESE GROUP IN EACH PREFECTURE?

Japan has a growing population of people of foreign origin. But the foreign population is not the same everywhere. In Osaka and the surrounding region the Koreans are the main foreign group, while in other areas it's Brazilians, many of whom are at least part Japanese. In Tokyo and most prefectures it is the Chinese, while in Okinawa, thanks to the military bases to defend Japan against Koreans and Chinese, it is the Americans.