The result was 13.3% for conscription, 39.6% for economics, 17.3% for marriage and family, 9.5% for study/academic, 20.2% for other reasons and 0.2% for unknown.
In 1939, labor shortages due to World War II led to organised official recruitment of Koreans to work in mainland Japan, initially through civilian agents, and later directly, often involving elements of coercion or deception.
Koreans claimed that Japanese land and production confiscation initiatives against Korean farmers during the 1910s caused a wave of forced migrants during the 1920s, while Japanese claim that Japanese colonisation kick-started Korea's defunct feudal economy and that majority of immigration was due to voluntary immigration seeking better economic opportunities.
During World War II, a large number of Koreans were also conscripted by Japan.
Restrictions of passage from Korean peninsula (April 1919-1922), 1923 Great Kantō earthquake, restrictions of passage from Busan (October 1925), opening of independent travel service by Koreans between Jeju and Osaka (April 1930), Park Choon-Geum was elected for the House of Representatives of Japan (February 1932), removal of restrictions of civil recruit from Korean peninsula (September 1939), public recruit from Korean peninsula (March 1942), labor conscription from Korean peninsula (September 1944), the end of WWII and the beginning of repatriation (1945), Cheju Uprising (April 1948), the Korean War (June 1950), the Home-coming Movement to North Korea (December 1959-1983), Treaty on Basic Relations between Japan and the Republic of Korea (1965), (1977-1983), Japanese ratification of the Convention Relating to the Status of Refugees (1982), 1988 Summer Olympics in Seoul, South Korea, 1997 Asian Financial Crisis Japan was connected to mainland Asia by at least two land bridges in north and south and was peopled by people from the mainland (see History of the Japanese people).
In late prehistory, in the Iron Age Yayoi period (300 BC to 300 AD), Japanese culture some Korean influence, though whether this was accompanied by immigration from Korea is debated (see Origin of the Yayoi people).
Following this, from 1950 onwards, Zainichi Koreans were allowed to voluntarily re-register their nationality as such.
Japan's defeat in the war and its loss of sovereignty over the Korean peninsula and Taiwan left the nationality status of Koreans and Taiwanese in an ambiguous position in terms of law.The division on the Korean peninsula led to division among Koreans in Japan.Mindan, the Korean Residents Union in Japan, was set up in 1946 as a pro-South offshoot of Chōren (League of Koreans in Japan), the main Korean residents' organisation, which had a socialist ideology.The Alien Registration Ordinance (, Gaikokujin-tōroku-rei) of ruled that Koreans and some Taiwanese were to be provisionally treated as foreign nationals.Given the lack of a functional nation on the Korean peninsula, Koreans were provisionally registered under the name of Joseon (Korean: ), the old name of undivided Korea.
In 1948, the northern and southern parts of Korea declared independence individually, making Joseon, or the old undivided Korea, a defunct nation.