The book presents a counter-argument to the widely held view that the Japanese have believed that they are a homogeneous nation since the Meiji period. Eiji Oguma demonstrates that the myth of ethnic homogeneity was not established during the Meiji period, nor during the Pacific War, but only after the end of World War II. The study covers a large range of areas, including archaeology, ancient history, linguistics, anthropology, ethnology, folk law, eugenics and philosophy, to obtain an overview of how a variety of authors dealt with the theme of ethnicity. It also examines how the peoples of the Japanese colonies, Korea and Taiwan, were viewed in the prewar literature on ethnic identity.