Are they really? Japan has probably the second navy in the world and is a massive technological power, while South Korea is an innocuously small industrial superpower (see: recent massive defense contracts with Poland).
According to the latest S&P Global Maritime & Trade newbuilding data, Chinese shipbuilders picked up the lion’s share of shipbuilding contracts during the third quarter of 2021 with some 68% in terms of gross tonnage (GT), of all new orders in Q3 2021 being placed in China.
ihsmarkit.com
South Korea is a tough competitor against tens of times larger China for the title of world's largest shipbuilder, Japan is third, and the rest of the world, including USA, EU, Russia, India, doesn't really matter much.