This study analyzes the change in the pricing of domestic and colonial rice in Japan during the interwar period. Japan was an empire that had thriving colonial trades to procure primary products. Colonial rice differed in quality from domestic rice because of climate conditions, and the government promoted homogenizing various types of rice. Consequently, colonial rice consumption expanded in Japan, and the pricing of each heterogeneous rice partially influenced the others after the mid-1930s. The forging of a closer relationship among the regions within the empire structurally transformed not only colonial economies but also the metropole's economy.