The first and last joint rally of Japanese, Korean, and Soviet workers to mark International Workers' Day took place in Station Square in the town of Toyohara (formerly Vladimirovka, later Yuzhno-Sakhalinsk) on 1 May 1946. That same day, there were also mass Communist-led rallies in Japan, the so-called “Shuntō,” or National Spring Offensive, against the US occupation.

Since 1855, Sakhalin Island has been considered jointly owned by Russia and Japan. In 1875, Russia acquired ownership of Sakhalin in its entirety, giving the northern Kuril Islands to Japan in return. Following Russia's defeat in the Russo-Japanese War of 1904-1905, Moscow was forced to cede South Sakhalin (territories south of the 50th parallel) to Tokyo. Following the victory over Japan during World War II, the Soviet Union grabbed the entire territory of Sakhalin Island and all of the Kuril Islands for itself.

In 1946, 305,800 people lived in South Sakhalin, including 277,600 Japanese and 27,000 Koreans.

In December 1946, the Soviet Union and the United States reached an agreement on the repatriation of the Japanese population. To replace the workforce, the USSR resettled scores of workers to Sakhalin and the Kuril Islands from various regions of the Soviet USSR.

Sources: “History of Sakhalin Oblast from Ancient Times to the Present Day,” Yuzhno-Sakhalinsk: Sakhalin Book Publishing House, 1995.