China’s military presence worldwide has been eminent and Japan’s response to this development to protect its land is to create its first marine unit since World War II. The new unit, called the Amphibious Rapid Deployment Brigade, was created in 2018 with now 3,000 troops. This is supported and trained by the US Marine Corps. However, their mission is very different from China because the unit is only meant to be a purely defensive force that would be just one part of Japan’s response to an attack in its territory especially to the Senkaku Islands.
Source: https://www.businessinsider.com/how-chinas-marine-corps-compares-to-japans-amphibious-force-2020-8