At the time of Japan's annexation of Korea in 1910, only several thousand Koreans lived in the main Japanese islands. This population largely consisted of students, merchants, and workers who entered Japan during the first four decades or so after the Meiji Restoration in 1868.
In the 1920s, the Japanese economy experienced a shortage of labor. In response, Koreans seeking better educational and employment opportunities migrated to Japan. Until the late 1920s, most were male migrant workers who frequently shifted occupations. Most ethnic Koreans were farmers from three southern provinces in Korea (North and South Kyongsang and South Cholla, including Chejudo). Since many were poorly educated and illiterate, Korean workers engaged in manual and menial work, along with Burakumin and Okinawans. In particular, Korean workers dominated jobs in construction and mining. By 1930, ethnic Koreans constituted a recognizable social group in major Japanese cities. They often received much lower wages than ethnic Japanese and congregated in Korean ghettoes because of poverty and discrimination. In the 1930s, Korean families began to settle down in Japan and the demographics expanded to include women and children. By the mid-1930s, almost a third of Koreans were born in Japan. Between 1920 and 1930, the number of Koreans in Japan increased over tenfold to 419,000.
While Korean immigration to Japan prior to World War II was largely voluntary, wartime labor shortages led to enforced migration. Both ethnic Japanese and Koreans colluded in the conscription of Koreans, men and women, to work in factories and mines. Between 1939 and 1945, the Japanese government brought 700,000-800,000 Koreans to work in Japan. Over 200,000 ethnic Koreans fought for the Japanese empire. By 1945, the number of Koreans peaked at approximately 2 million. Many Koreans in Japan suffered war-related injuries and deaths (approximately 239,000 according to some scholars). Up to 30,000 ethnic Koreans died in the atomic bomb explosion in Hiroshima.
Following Japan's defeat in World War II, the majority of ethnic Koreans (1-1.4 million) left Japan. By 1948, the population of ethnic Koreans settled around 600,000. These Koreans and their descendants are commonly referred to as Zainichi (literally "residing in Japan"), a term that appeared in the immediate postwar years. Since the end of World War II to the present, the number of Zainichi Koreans has lingered around the same figure.
Ethnic Koreans who remained in Japan did so for diverse reasons. Koreans who had achieved successful careers in business, the imperial bureaucracy, and the military during the colonial period or who had taken advantage of economic opportunities that opened up immediately after the war–opted to maintain their relatively privileged status in Japanese society rather than risk returning to an impoverished and politically unstable post-Liberation Korea. Some Koreans who repatriated were so repulsed by the poor conditions they observed that they decided to return to Japan. Other Koreans living in Japan could not afford the train fare to one of the departure ports. For ethnic Koreans who had ethnic Japanese spouses and Japanese-born, Japanese-speaking children, it made more sense to stay in Japan rather than to navigate the cultural and linguistic challenges of a new environment.
Although Koreans in Japan prior to World War II suffered racial discrimination and economic exploitation, the Japanese authorities nonetheless counted ethnic Koreans as Japanese nationals and sought to fully assimilate Koreans into Japanese society through Japanese education and the promotion of intermarriage. Following the war, however, the Japanese government defined ethnic Koreans as foreigners, no longer recognizing them as Japanese nationals. The use of the term Zainichi, or "residing in Japan" reflected the overall expectation that Koreans were living in Japan on a temporary basis and would soon return to Korea. By December 1945, Koreans lost their voting rights. In 1947, the Alien Registration Law consigned ethnic Koreans to alien status. The 1950 Nationality Law stripped Zainichi children with Japanese mothers of their Japanese nationality; only children with Japanese fathers would be allowed to keep their Japanese citizenship. As of 1952, former colonial subjects–the majority of whom were Korean--whose homeland was not recognized by Japan as a legitimate nation-state (including Korea) were rendered stateless. In 1955, a law required that all registered foreigners be fingerprinted. Ethnic Koreans were even excluded from the rights granted to non-nationals in Japan's postwar constitution. Employment policies excluded Koreans from all "Japanese" jobs after 1945. Barred from all public and private-sector employment, Koreans pursued jobs in the informal-sector and engaged in illegal or marginal economic activities such as illegal alcohol production, scrap recycling, and racketeering.
Postwar ethnic Korean organizations provided economic assistance and fought for ethnic Korean rights. The pro-North Korean, pro-Communist organization, the General Federation of Resident Koreans in Japan, usually called Soren or Chongryun–became one of the most influential. In addition to providing loans for ethnic businesses, Soren established ethnic schools that taught Korean language and history to prepare students for eventual return to Korea. In contrast to the miserable status of Zainichi in Japan and the lagging economy and autocratic dictatorship in South Korea, Soren projected North Korea as a Communist paradise to which all Koreans would one day return, a vision that seemed viable in the 1950s given the Communist Party's support for Koreans before and after World War II and the economic success of North Korea over South Korea during that period. Throughout the 1950s, Soren won the support of more than 90 percent of ethnic Koreans in Japan.
In the late 1950s, Soren launched a repatriation project that dispatched a total of 93,340 people to North Korea, including 6,731 Japanese. Approximately 70,000 Zainichi repatriated during a two-year period from 1960 through 1961. The numbers dropped dramatically the following year, however, and the repatriation project effectively ended in the early 1960s (Officially, the project ended in 1984). When North Korean poverty, corruption, and autocracy became apparent, Soren membership began to decline. Membership declined even further when Japan established formal diplomatic relations with South Korea through the 1965 Normalization Treaty. The treaty provided incentives for Koreans in Japan to seek South Korean citizenship, including a functional South Korean passport, freedom to travel, and access to Japanese medical and welfare benefits.
Large-scale repatriation to South Korea, however, did not occur. Many Zainichi living Japan–a democratic country that had just entered a period of rapid economic growth and prosperity–found life in South Korea under the autocratic military dictatorship of Park Chung Hee in the 1960s and 1970s an unattractive alternative. Also, Zainichi Koreans had by then become too entrenched in Japanese society. Ethnic Koreans in Japan were culturally and linguistically Japanese. In addition, Zainichi Koreans who returned to North Korea in the late 1950s and early 1960s (during the repatriation project) or to South Korea in the late 1960s (following the 1965 Normalization Treaty) experienced suspicion and rejection by the respective governments as well as homeland compatriots. In the North Korean class system, Zainichi were treated as second-class citizens and suspected as spies for the South or Japan. Second-generation Zainichi travelers to South Korea in the 1960s and 1970s often received hostile treatment by South Korean immigration authorities and co-nationals.
Despite the prospect of permanent settlement in Japan, few ethnic Koreans chose to naturalize as Japanese citizens. Only 233 Koreans were naturalized in 1952. In the 1950s and 1960s, the figure fluctuated between the 2,000s and 3,000s. This was because naturalization was considered taboo among the Zainichi population; it was an act of ethnic betrayal, a rejection of Zainichi experience and identity, and tantamount to treason. Naturalized or mixed Zainichi often suffered double exclusion. Since the Japanese government portrayed Japan as an ethnoracially homogenous society, ethnicity became synonymous with citizenship. Until the late 1980s, naturalization required the adoption of Japanese-sounding names and compliance with the Japanese practice of household registration (or koseki). Moreover, naturalization did not guarantee protection from anti-Korean discrimination or eliminate fear of exposure of one's Korean ancestry.
In the first quarter-century following World War II, ethnic Koreans in Japan continued to face systematic exclusion and discrimination–in education, employment, housing, and marriage. Barred from all public-sector jobs and prestigious professions and occupations, the Zainichi population created an ethnic economy in self-employed, service, and entertainment sectors that targeted principally Japanese customers (such as yakiniku restaurants and pachinko parlors). Until the 1980s, despite their equal treatment as taxpayers, Zainichi faced barriers to receiving medical, welfare, pension, and other safety nets and public services.
In the 1970s, new social movements and intellectual currents encouraged ethnic mobilization and the assertion of a Zainichi identity. For example, Koreans led an anti-fingerprinting movement and a "real-name" initiative that asserted the ethnicity of naturalized Koreans. Some sought to create a Koreatown. Others sought to win local suffrage rights. After more than a decade of Zainichi political activism, local authorities started to hire Korean nationals for civil service positions by the early 1980s. By the mid-1980s, the proportion of ethnic Koreans in medical and scientific fields was twice that of the ethnic Japanese population. In 1985, revision of Japan's nationality laws eliminated the patrilineal descent of citizenship. In 1987, it became possible for naturalized Koreans to keep their ethnic Korean names. By 1991, permanent residency status was granted to almost the entire Zainichi population. By 1993, the demeaning practice of forced fingerprinting during alien registration for permanent residents was abolished. Educational and employment gaps between ethnic Japanese and ethnic Koreans narrowed considerably by the 1980s.
By the 1990s, the legacy of colonialism and racism had clearly waned. Sports, tourism, and Korean popular culture raised Japanese interest in South Korea. Both pressure from the international community as well as from domestic social groups increased awareness and changed Japanese attitudes about discrimination towards ethnic minorities. In the 2000s, South Korean celebrities and third-generation Zainichi openly and proudly announced their Korean heritage. By the early twenty-first century, over 10,000 Zainichi chose to naturalize every year. In contrast to first-generation Zainichi who had experienced the darkest decades of exclusion and discrimination in the 1950s and 1960s, successive generations who came of age no longer took for granted that naturalization was an act of ethnic betrayal. Rather, many Zainichi today consider naturalization as a matter of individual choice and embrace the possibility of a Korean-Japanese identity.