This work analyzes the international meaning of community in the 1930s East Asia. In order to understand the transformation of community concept from a social to an international one, this analysis explores how toa kyodotai emerged in Japan, why it became an international relations concept, and what political consequences it created as it diffused into colonial Korea. Paradoxically, the concept was devised by a Tenko (converted) in Japan and accepted by a Korean counterpart who had vehemently fight against Japanese colonialism. Such diffusion was predicated on three considerations: the future of Sino-Japanese War and Tripartite Alliance, potential of Japanese community moving beyond Western liberalism, capitalism and nationalism, and the relationship between Toa kyodotai and Chosun`s independence.