The dominant country in Asia always desires to establish a regional financial institution to assume some exclusive leadership. Japan, which established Asian Development Bank (ADB) in the 1960s and proposed Asian Monetary Fund (AMF) in the 1990s, was in such a position in the past, but it is now China that is keen to establish regional institutions. In this context, China’s Asia Infrastructure Investment bank (AIIB) is not a surprising proposal. What is unique with regard to AIIB is the reaction of the US. While it successfully blocked Japan’s AMF proposal from inside, it attempted to block AIIB from outside without success. Institutional configuration, especially the parity between the dominant powers, is also important for an institution to be successfully established. When two (or more) countries agree to accept equal footing, a regional institution is likely to come into existence. Other countries also feel comfortable with an organization where no single country becomes too dominant. There is parity between Japan and the US in ADB and that between Japan and China in ASEAN+3 Macroeconomic Research Office (AMRO) and Chiang Mai Initiative Multilateralization (CMIM). AIIB could be dominated by a single country, unless the US and Japan participate.