Ōizumi (大泉町 Ōizumi-machi) is a town located in Ōra District, Gunma Prefecture, in the northern Kantō region of Japan. As of February 2015, the town had an estimated population of 39,996 and a population density of 2220 persons per km². Its total area was 18.03 km². Approximately 10% of the total population are foreign citizens, mostly Japanese Brazilians, who work at many factories in the town. Since 1990, Japanese descendants from foreign countries have been permitted to stay in Japan freely. It is estimated that 15% of the population speak Portuguese as their native language, and as of 2007 Ōizumi has the highest concentration of Brazilians of any city in Japan.