What motivated Japan to look at South Asia as a foreign aid destination? This paper explores the evolution of the Japanese attitude toward South Asia in foreign aid. Japan began sending official development assistance (ODA) to the region as early as 1958 and has become one of its largest contributors. However, Japan’s ODA goals to the region have been underexplored. Japan has expanded economic diplomacy by capitalizing on the policy of development cooperation to the region and recently stretched it out to the security building cooperation with aid recipients in South Asia, especially with India. By examining the foreign aid policy change in Japan, the paper argues that the attitude of Japanese policymakers favoring South Asia as the Japanese ODA destination is closely associated with strategic necessities, which are Japan’s neo-mercantilist interests that is aims to achieve in the region while deploying development cooperation activities. It analyzed how Japan has changed its attitudes toward aid to South Asia from a neo-mercantilist to the idealist and constructivist approach, again to the neo-liberalist, and further to the neo-mercantilist stance. It also discusses how South Asia can serve Japan’s neo-mercantilist interest in the realm of foreign aid.