Were the Korean Peninsula and Japanese Island developed by ancient China immigrants?

According to some data, Japanese aborigines are not of China origin, but have been rounded up in Hokkaido. Others should be descendants of China, especially in the Song Dynasty. When Japanese women want to get married, they always try their best to come to China and get pregnant with Dasong's children, so as to marry a good family. You said that Japan is descended from China, which is recorded in historical data. Not only Japan, but also countries around China are proud that their wives are pregnant with Dasong's children.