“During the 1930s and 1940s, the Japanese government linked eugenics to nationalism by arguing that Japan's national strength depended on the biological quality of its citizens.”

The report explains how, from the Meiji era, arguments for "improving the Japanese race" (nihon jinshu kaizōron) developed in the context of striving to keep up with the Western powers. It notes that after the Russo‑Japanese War this discourse "gradually came to take on a more nationalistic coloration," with thinkers stressing that improving the physical and mental qualities of the people was necessary so that, "in the struggle for survival among the nations of the world, the fortunes of the state might advance and national prestige be enhanced." This intellectual background is presented as part of the genesis of the National Eugenic Law enacted in 1940.

The House of Councillors' report, in tracing the legislative background to the 1948 Eugenic Protection Law, describes how earlier eugenic thinking in Japan connected biological improvement to national strength. It notes that after the Russo‑Japanese War, "arguments that the physical and mental improvement of the Japanese was urgent in order to advance the nation's fortunes and display national prestige in the global struggle for survival" took on a stronger nationalist tone. These currents are described as part of the ideological context for the National Eugenic Law of 1940 and subsequent policies.

In the foreword, the Institute of Population Problems explains the purpose of the Eugenic Protection Law as follows: "The Eugenic Protection Law was enacted for the purpose of preventing the birth of inferior descendants and for protecting the life and health of mothers, thereby contributing to the improvement of the national quality." The text repeatedly uses expressions such as "national quality" and speaks of preventing the birth of "inferior descendants" in order to "contribute to the prosperity of the nation," explicitly tying the biological quality of citizens to national welfare.

Regarding the 1940 National Eugenics Law, the article notes that it "mainly focused on stamping out bad heredity, for the sake of the improvement of the nation’s racial hygiene" and describes it as part of "Japan’s eugenic policy" that aimed to "prevent the spread of poor-quality genetic traits." It explains that eugenics in prewar and wartime Japan was closely connected to state goals, with policies justified as necessary to "strengthen the national body" and secure the future of the nation through control of hereditary ‘quality’.

In the chapter on Japan in ‘Eugenics in East Asia’, the author explains that Japanese policymakers in the 1930s and 1940s framed eugenics as part of national policy: “The National Eugenic Law of 1940 sought to control reproduction to improve the ‘quality’ of the Japanese people, and was justified as necessary for national defence and the strength of the empire.” The text highlights that Japanese eugenicists “conflated national strength with the biological fitness of the population,” arguing that the future of the nation depended on healthy, ‘superior’ citizens.

Robertson writes that "The new scientific order in Japan was introduced under the aegis of nationalism and empire-building." She argues that in Japan around 1900, "science that took up the ‘positive’ meaning of blood as its subject was eugenics and race science, and it fueled a discourse that permeated all aspects of everyday life in Japan." This discourse was "premised on a future-oriented vision of a racially improved nation-state, one peopled by taller, heavier, and more intelligent Japanese" and framed the population as a "national body" whose hereditary quality had to be improved for the sake of national strength.

The lecture notes explain that in modern Japan eugenics developed differently from Europe and the US because it was strongly tied to “the policy of enriching the country and strengthening the military that supported the modern imperial system state.” In the third phase (1920s–1940s), “eugenics was developed as a social movement” and there was a move toward legislation, culminating in the 1940 National Eugenic Law. The text notes that the Ministry of Health’s concept of “racial hygiene” was “strongly influenced by German racial hygiene,” and that from 1934 to 1938 bills for a ‘National Eugenic Protection Law’ were repeatedly submitted to the Imperial Diet, showing that improving the ‘race’ or ‘people’ biologically was treated as part of national policy.

The report notes that in October 1939 the "National Physical Strength Council" (Kokumin Tairyoku Shingikai) was established and that a national‑ethnic eugenic system was deliberated there. Following consultation with expert committees, "the National Eugenic Law of 1940 was enacted on the basis of the government bill." The Council's mandate linked the strengthening of the nation's physical fitness and the selection of healthy offspring to wartime national objectives, illustrating how eugenics policy was framed as serving the strengthening of the state.

Historical Background: Leading up to World War II, the Japanese government used eugenic ideas to promote legal sterilization and elimination of those who were judged to be inferior. In 1940, the Imperial Japanese Parliament enacted a National Eugenic Act in the cabinet of Prime Minister Konoe, targeting persons with intellectual and genetic disabilities. According to Yoko Matsubara, 454 people were sterilized in the five years from 1940 to 1945. The Eugenic Protection Act labeled people with disabilities as "defective offspring" from before birth, denying their existence with the aim of propagating only the "superior" citizens.

This dissertation on interwar Japan notes that during the 1910s–1930s there was "a growing call among social scientists, social reformers, and government elites to solve ‘population problem (jinkō mondai).’" It explains that "population issues—particularly, birth control, eugenics, and population policy—continuously interwove sexual and biological issues with politico-economic ones" and constituted "a crucial stage for reconstructing Japanese modernity through integrating scientific progressivism, social reformism, and imperial nationalism." It emphasizes how discourses on population "constituted and categorized desirable bodies to reproduce," linking biological ‘quality’ to the needs of the nation-state.

The article traces how eugenic thought spread in 1930s Japan up to the promulgation of the National Eugenic Law on 1 May 1940. It explains that eugenics, defined after Galton as a discipline dealing with “all influences that improve the inborn qualities of a race,” was presented as a future‑oriented practical science to increase the value of individuals and particular groups. Based on articles in the women’s newspaper Fujin Shinbun, the author shows that concerns about population, ‘racial’ quality, and national strength were linked in public debate and that “along this line of extension the National Eugenic Law was enacted in 1940,” indicating a perceived connection between biological ‘quality’ and the strength and future of the nation.

This historical paper on the Japanese Society of Psychiatry and Neurology and eugenic legislation describes eugenic and sterilization policies as “a nationalistic and ethnic‑nationalistic population eugenic policy” directed at mental illness, intellectual disability, and ‘psychopathic’ persons via genetics. It notes that these policies were linked to population policy, and that in pre‑war Japan psychiatrists participated in discussions that treated the improvement of the ‘race’ or ‘people’ through eugenic measures as a way to strengthen the nation. The author characterizes this as part of a broader ‘population eugenic policy’ under the modern state.

Chapter Four contrasts the decline of race science and eugenics in the West with their efflorescence in postwar Japan, where conditions of occupation heightened the relevance of racial eugenics as a prescription for national unity and strength. The author argues that an ideology of "pure blood" became a basis for reconstructing Japanese nationalism after the war, and that geneticists and anthropologists who identified as having "pure Japanese blood" never questioned that biopolitical category. They thereby constructed the Japanese as a racial community bounded by "pure blood," linking the biological quality of citizens to the strength and unity of the nation.

This report on population issues and family policy in the Meiji, Taishō and Shōwa eras notes that in 1905 Japan’s first eugenics journal was founded and that later policies sought “to preserve the eugenics of the race by implementing birth control, segregation and sterilization for people with hereditary diseases.” It emphasizes that eugenic movements, corresponding to concerns about the ‘quality’ of the population, were promoted alongside population and family policies from above. While not using the word ‘nationalism’ directly, the report situates these eugenic policies within state efforts to manage and strengthen the national population in the early Shōwa period, including the 1930s and 1940s.

Summarizing earlier work on the 1940s sterilization laws, the article notes that Matsubara Yōko’s 1998 study "The Enactment of Japan’s Sterilization Laws in the 1940s: A Prelude to Postwar Eugenic Policy" showed how wartime eugenic measures were designed to improve the "quality" of the population. The author explains that educational discourse in the late 1940s and 1950s adopted eugenic concepts of "ability" and "quality" of children that were tied to the idea of cultivating a healthy and capable national body, reflecting a continuity between eugenic thinking and ideas about the nation’s strength.

This article focuses on the 1940 National Eugenic Law and its legacy but emphasizes its wartime ideological context. It explains that the law ‘aimed to prevent the birth of inferior offspring and to promote the propagation of superior offspring’ and that such goals were framed in contemporary government discourse as measures to ‘protect and strengthen the nation.’ The author notes that bureaucrats and medical experts described the Japanese population as the ‘basis of national power’ and used eugenic rhetoric about hereditary fitness to argue that the biological quality of citizens was crucial to Japan’s survival in international competition and war.

The article traces how Japanese officials adapted eugenic and racial ideas from abroad, stating that by the 1930s, ‘population studies emerged as an “objective” scientific field’ but in practice shared eugenics’ interest in differential fertility between classes and races. It notes that public health leader Koya ‘insisted that the Japanese needed to increase their population in order to effectively rule their Korean colony,’ and that he used ‘the common eugenic argument that “lower” races typically outnumbered the “advanced” ones’ as a warning. In this framing, enhancing both the size and biological quality of the Japanese population was presented as necessary to sustain imperial rule and national power.

The essay explains that Japan's National Eugenic Law of 1940 was drafted under the wartime total‑mobilization system and that it "reflected eugenic thought" while being shaped by debate in the Imperial Diet. It notes that the law was submitted by physician‑politician Yagi Itsurō, based on a "sterilization bill" prepared by the Japan Ethnic Hygiene Association, itself influenced by Nazi Germany's Law for the Prevention of Hereditarily Diseased Offspring. The author situates the National Eugenic Law alongside the 1938 National General Mobilization Law and the creation of the Ministry of Health and Welfare, framed as measures to improve the physical strength of the nation during the war.

The article notes that in Japan, "the eugenic policy of artificially prioritizing the preservation of healthy offspring" began with the wartime National Eugenic Law on sterilization and abortion enacted in 1940. It then explains that after the war this became the model for the 1948 Eugenic Protection Law, describing a continuity in state policy that treated the biological "quality" of the population as a matter of public concern linked to national goals.

This reproduction of material on the National Eugenic Law's legislative process describes how eugenics ideas spread in Japan in tandem with discourses on racial improvement and national strength. It notes the emergence of arguments that, in an empire like Japan which "respects the unique genealogy of the nation," improving the biological traits of the people was necessary for the empire to maintain a superior position in the world, linking eugenic thinking explicitly to nationalist ideology.

Some historians of modern Japan caution against overstating the coherence of a state ideology that fused eugenics and nationalism. They argue that, although eugenic rhetoric about improving the population was common among certain bureaucrats, doctors, and intellectuals in the 1930s–1940s, Japan’s wartime mobilization drew on multiple, sometimes contradictory, ideological strands (emperor-centric loyalty, spiritualism, pan-Asianism) that did not all emphasize biological determinism. In this view, eugenics was one important thread in policy debates, but not the singular or defining basis of conceptions of national strength.

The narration states that by the late 1930s, "Japanese society was a highly regimented fascist state, and this is when eugenics in Japan became public policy." It continues: "Sterilization and segregation of people who were deemed 'unfit' became policy. In 1940, the military pushed through the National Eugenic Law, the law that allowed the government to forcibly" intervene in reproduction. Earlier in the video, eugenics campaigns are described as encouraging the "right" people to reproduce and discouraging workers, the uneducated, and Koreans from having children, presenting these policies as part of a broader project to mold the population in line with national goals.