The victory of the Bolsheviks in Russia in 1917 and their hopes for a world revolution led to the establishment of the Comintern (a contraction of Communist International, the organization founded in Moscow in 1919 to coordinate the world communist movement). The Comintern realized the importance of Japan in achieving successful revolution in East Asia and actively worked to form the Japan Communist Party (Nihon Kyosanto), which was founded in July 1922. The announced goals of the Japan Communist Party in 1923 were an end to feudalism, abolition of the monarchy, recognition of the Soviet Union, and withdrawal of Japanese troops from Siberia, Sakhalin, China, Korea, and Taiwan. A brutal suppression of the party followed. Radicals responded with an assassination attempt on Prince Regent Hirohito. The 1925 Peace Preservation Law was a direct response to the "dangerous thoughts" perpetrated by communist elements in Japan.

The liberalization of election laws, also in 1925, benefited communist candidates even though the Japan Communist Party itself was banned. A new Peace Preservation Law in 1928, however, further impeded communist efforts by banning the parties they had infiltrated. The police apparatus of the day was ubiquitous and quite thorough in attempting to control the socialist movement. By 1926 the Japan Communist Party had been forced underground, by the summer of 1929 the party leadership had been virtually destroyed, and by 1933 the party had largely disintegrated...

The Peace Preservation Law of 1925 gave police the authority to arrest people for "wrong thoughts." Special Higher Police were created to regulate the content of motion pictures, political meetings, and election campaigns.