The Regional Comprehensive Economic Partnership (RCEP) took effect on the first day of the new year. Involving China and 14 other countries, the deal is now considered the largest free trade agreement in the world and is expected to benefit retail consumers. RCEP countries have promised to drop tariffs on 90 percent of goods traded in the Asia-Pacific region, widening consumer choice at even cheaper prices.

China's trade with Japan as a result of the deal could be particularly significant. To date, the two countries have never signed a single bilateral trade deal. But under the RCEP, there will be zero tariffs on more than 80 percent of goods from both countries over time.

China has already signed trade deals with most of the RCEP countries including ASEAN, Australia, New Zealand and South Korea, but no reciprocal deal with Japan. So trade between China and Japan could change with the enforcement of the RCEP, Xu Mingqi, senior advisor at Shanghai Academy of Social Sciences, told CGTN.

"The effects will not immediately increase because we already have free trade agreements with ASEAN, Australia, New Zealand and South Korea. Their products already come into the Chinese market with low tariffs. But we do not have free trade agreements with Japan yet, so it will be easier for Japanese goods coming into China and prices will go down," said Xu.

But the "zero tariff" promises will not be enforced immediately. According to the RCEP deals, for example, Japanese sake is levied with a tariff of 40 percent when coming to China at present, but that tariff is due come down to zero in 2043. Similarly, China's Shaoxing rice wine will also enjoy no tariffs to enter Japan in the same year.

Though the move will be put into different phases from 2022, the benefits are expected to be huge. Data from the Ministry of Commerce show that in the first half of 2021, trade between China and Japan reached nearly $181.3 billion, a year-on-year increase of 23.7 percent. And experts expect that figure to continue to rise in the coming years.

In addition to China's trade with Japan, one other thing that will bring obvious impacts is the opening up of the service sector. RCEP countries have committed to opening service industries like finance, telecommunications and tourism. The 15 nations have also promised to release a negative list within six years.

Xu said this will mean more opportunities for Chinese companies. "Service-oriented e-commerce platforms like  Alibaba and Tencent will have more opportunities to export their products and it may be easier for them to invest in these countries," he added.

A report from the Peterson Institute for International Economics estimates that by 2030, the RCEP will inject additional exports values worth $519 billion to the countries involved. The report also says incomes will collectively grow by $186 billion for workers in the region.