As a result, the Tanaka government's[1] Ministry of Justice created a "thought section" to target left-wing groups.
Starting on March 15, multiple offices and homes were raided and 3,500 arrests were made over the entire year.
[5] On that one day, 600 to 700 suspected communists were arrested - later, half of them were found guilty.
[6] The fledgling Japanese Communist Party (JCP) was dealt a major blow by the arrests of April 16[1] and forced underground.
[7] This led the Soviet Union, which had supported the JCP, to turn its focus to China instead of Japan for a communist revolution.