In 1882, 4 people first immigrated to Japan and according to records 790 Koreans resided within Japan in 1909, during this time foreign employment was prohibited therefore most were students, with a handful of diplomats and some political refugees. One of the reasons Koreans left for Japan was the land survey project the Japanese had started. After their land was taken from them during the land surveys, many were forced into peasantry and the number of peasants increased greatly. Farmers who had lost their jobs and livelihoods boarded the ships to Japan as their next best option.
After 1931 and the effects of the Manchurian Incident, Sino-Japanese War(1938), World War II , Japan desperately needed a labor force within its country and from this time on forced mobilization of laborers begun. Korean workers were dragged to various Japanese colonies to mine and work. Including soldiers, close to 1 million were forcibly mobilized and it is estimated that roughly 80,000 were forced to be comfort women.
After Japan lost the war 1.04million made their way back to Korea till 1950. Nevertheless 20% of the original population of Korean residents living in Japan (600,000) stayed. They were mostly those with weak ties to Korea, Korean- Japanese that had made their fortunes in Japan and those who after Korea’s liberation felt anxiety at the extreme left and right opposition and gave up their return to Korea.