Antisemitism in Japan has developed over the years despite the presence of a relatively small and obscure Jewish population. Japan had no traditional antisemitism until nationalist ideology and propaganda began to spread on the eve of World War II. Before and during the war, Nazi Germany, an ally to the Japanese, encouraged Japan to adopt antisemitic policies. In the post-war period, extremist groups and ideologues have promoted conspiracy theories.

In 1918, the Imperial Japanese Army sent troops to Siberia to cooperate with the White movement. White Army soldiers had been issued copies of The Protocols of the Elders of Zion, and Japanese soldiers first learned about antisemitism. The Protocols continue to be used as evidence of Jewish conspiracies even though they are widely acknowledged to be a forgery.

According to Dr. David Kranzler:

The key to the distinction between the Japanese and the European form of antisemitism seems to lie in the long Christian tradition of identifying the Jew with the Devil, the Antichrist or someone otherwise beyond redemption...The Japanese lacked this Christian image of the Jew and brought to their reading of the Protocols a totally different perspective. The Christian tried to solve the problem of the Jew by eliminating him; the Japanese tried to harness his alleged immense wealth and power to Japan's advantage.

In 1925 Captain Norihiro Yasue published the first translation of the Protocols in Japanese. A Russian-language specialist, he was assigned to the staff of General Gregorii Semenov, a vehement anti-Semite who distributed copies of the Protocols to all of his troops. Along with a few dozen other Japanese soldiers, Yasue read and accepted the premises of the Protocols, and contributed for a time to various antisemitic publications, including Kokusai Himitsu Ryoku no Kenkyu (国際秘密力の研究, Studies in the International Conspiracy), under the pen-name Hō Kōshi. He later changed his views when in 1940 Japan signed the Tripartite Pact which formally sealed Japan's alliance with Nazi Germany. His newly pro-Semitic stance led to his dismissal from the Japanese Army.

During the 1930s Minetaro Yamanaka (山中峯太郎) wrote stories about the Yudayaka, the "Jewish Peril." A major journalist at the Tokyo Asahi Shimbun, Yamanaka was a prolific author of children's fiction who serialized the novel Daitō no Tetsujin (Superman of the Great Orient) from August 1933 until the end of 1934 in the periodical Shōnen Kurabu (Boys' Club), read mainly by Japanese boys between the ages of 8 and 12. The hero of this story is the detective Hongō Yoshiaki who battles the villain Sekima, head of the shadowy Zion Alliance, a Jewish secret organization seeking to undermine the Japanese Empire. A typical quote from Superman of the Great Orient:

There are about 13.5 million Jews scattered around the world. Hundreds of years ago they gobbled up all the world's wealth. Especially in the United States, Britain, France, and in other Western countries too, there are many rich Jews who do whatever they want with the money of the people...This wealth is used to increase the invisible Jewish power throughout Europe and the United States...These scary Jews have a secret society called the Zion Alliance. The goal of the Zion Alliance is...that all nations be ruled by Jews...This is a real global conspiracy.

Yamanaka stopped writing with the surrender of Japan in August 1945, but Kodansha Ltd. continued reprinting this series until the 1970s.^{[citation needed]}