The Introduction defines transnational Nazism as an ideological outlook that enabled Japanese and Germans to imagine a binational community before their governments forged the Axis alliance. Because of economic and technological limitations, the mass media was essential in fostering interwar German-Japanese mutual identification. Japanese transnational Nazis found Hitler and elemental National Socialism appealing, while German transnational Nazis accommodated the non-Aryan Japanese. It reviews the extant scholarship on Japanese-German relations and points out that there is a gap in knowledge of the 1920s. The book contributes to Japanese historiography by engaging in debates on fascism and militarism. It intervenes in German historiography on orientalism and Nazism. It also adds to our understanding of transnational history and the movement of right-wing extremism. The chapters are briefly introduced. The introduction ends with an overview of German-Japanese relations from 1914 to 1945.