This article discusses the changes in the role and function of Japanese schools in Brazil before and after WWII vis-a-vis the host country’s social and political environment, with emphasis on the pressure from nationalism on Japanese immigrants’ education exerted by the Vargas administration. The impact of the policy was both significant and turbulent. It had become one of the main causes of the drastic changes in the national identity and character of Japanese primary schools after the Pacific War, with tragic consequences for the Japanese immigrants. Before WWII, Japanese immigrants had gradually advanced their status from contracted labourers to independent farmers, forming Japanese colonias (settlements) on government-allocated uncultivated land. They were eager to give their children elementary level education, and in remote areas, they had no choice but to provide this education principally in the Japanese language. These schools therefore became targets of the anti-Japanese movement that began in the 1920s, peaked in the 1930’s, and was phased out in the 1940s. Just before WWII, however, President Getulio Vargas developed a nationalistic policy which encompassed education; foreign schools were oppressed, and in 1938, most Japanese primary schools were closed. In addition, there was a ban on holding meetings and public gatherings, and Japanese newspapers were abolished. This was a traumatic situation that made Japanese-Brazilians pessimistic about the future, and their despair pushed them closer to supporting the goals of their Japanese homeland. The conflict between Brazilian and Japanese nationalism took place in primary education, which saw a tragic confrontation among immigrant groups, and resulted in a radical change of public opinion, as well as in the primary schools themselves.