This study will follow an approach of the study of international politicaleconomy, a subfield of international politics, to discuss if and when Japanhas to ratify the TPP. The work will first analyze the establishment andmajor features of the liberal and open international economic and tradeorder under U.S. economic hegemony from the end of the Second WorldWar to the Cold War. Second, the discussion will center on evolutionarychanges of the GATT and WTO during the Cold War and the initial periodthereafter, where the U.S. put priority on security considerations overeconomic competition ones. Third, the study will capture a neo-liberaltransformation of the trade order after the post-Cold War period, leading toa dynamic competition of building FTAs in the Asia-Pacific region,particularly between the rising China’s regional hegemonic aspirant andthe relatively declining U.S. hegemon over the RCEP versus the TPP. Last,the study will conclude with a policy recommendation that stresses theneed of Japan’s maximal postponement in entering or completing TPPratification process, under uncertainties on China’s economic downturn andon growing U.S. populism and isolationism.