The debate on TPP versus RCEP has been widely recognized as a struggle between the United States and China for expanding their influence in the Asia-Pacific region, and it is now commonplace for scholars to discuss the rivalry between the two agreements. Both the TPP and RCEP agreements could invigorate the sluggish Asia-Pacific economy by promoting trade liberalization and economic integration; however, the story is not so simple because they have been recognized as being a political tool as well as economic drivers. An important change occurred on March 15, 2013 when Prime Minister Abe Shinzo announced that Japan would formally seek to join the negotiations to establish TPP, in which the United States leads. Japan became the 12th member of the negotiations at the 18th round on July 2013 and now leads the TPP negotiations with the United States. From its perspective, Japan’s participation in TPP might be the best option for revitalizing its economy and restoring its growth. At the same time, it caused the equilibrium between the competing TPP and RCEP to shift toward TPP.