Financial regionalism has become a trigger of Asian regionalism in the 90s. Japan utilized its economic, and financial potential to play an active role in the region in the face of financial crisis 1997-98, attempting to build prestige and support emerging regional frameworks as a leader and institution - supplier. The paper is studying Japan's financial regionalist policy since the 90s through the prism of intra- and extra-regional rivalry over leadership with, respectively, China, and the United States. An analysis is centred around the project of Asian Monetary Fund, announced by Tokyo in the wake of Asian financial crisis, however, blocked by the United States, and, to some extent, China. As a consequence of the global crisis 2007-2009, Chiang Mai Initiative has been multilateralized in the form of a single financial contract. Again, a debate on the Asian Monetary Fund project has been resumed. Finally, recent Asian Infrastructure Investment Bank project by China is addressed. The paper is an attempt to study the evolution of Japan's policy towards financial regionalism to understand hegemonic aspirations of Japan, while considering conflicts of interests of Tokyo, Beijing, and Washington. A theoretical context is drawn basing on financial regionalism and hegemonic stability theories.