The Asian crisis has revealed the vulnerability of regional monetary and financial arrangements, and the failure of Japan’s role as a leader. Detecting the lack of concert in regional monetary policy or a coherent strategy in preventing and solving regional economic crisis, the research asks why there has been relatively limited policy cooperation n the reorganization process of Pacific Asia. The key to understanding this region lies in leader-client dynamic and domestic factors that drive policy preferences. By focusing on the interactions of leader-client relations between Japan and two important Asian countries (Thailand and South Korea) in financial arrangements, the research examines how concert and discord of the leader and clients’ preferences arising from their respective perceptions, interests, and domestic institutional settings influence regional economic integration and the leaders’ policy leverage. The results of the finding will also be contrasted to my on-going research on the dollarization of Argentina.