The Regional Comprehensive Economic Partnership agreement takes effect Saturday, and Japan and other member nations expect free trade within the economic bloc to revitalize their pandemic-hit economies.

The outlook on its impact on Japan's economy is particularly rosy, some analysis suggests. At the same time, however, Japan will face difficulties keeping China's growing influence in the region in check, with its ally, the United States, remaining at odds with China over human rights and other issues.

"Japan would benefit the most from RCEP tariff concessions, largely because of trade diversion effects," a recent report published by the U.N. Conference on Trade and Development (UNCTAD) pointed out.