Sakhalin (Karafuto in Japanese) is a very long (1000 km) but narrow (200 km in its largest extent) island located between Hokkaido Island and Russia. It is separated from Asian continent by a narrow strait of 6 km width. Allong with the Kuril Islands, Sakhalin is one of the territories disputed between Japan and Russia and its belonging has not yet been definitely settled since WWII.

On August 8 1945, Russia began "Operation August Storm" and entered the war against Japan. On August 11, the Red Army crossed the 50th parallel, the frontier between 2 countries and advanced 100km southward on Sakhalin Island. On August 15, Japan accepted the declaration of Potsdam to end the war. Thousand civilians were killed by Russians, Three Japanese ships transporting refugees from Sakhalin were sunk by Russian Submarines with 1,700 killed. Fighting ended on August 22, with 600,000 Japanese, mostly soldiers from Sakhalin and Manchuria were brought to Siberia's labor camps and 60,000 never returned.