Because Toyohara was once known as Vladimirovka, and the Soviet's did help end the Pacific War, and Japan did...You know...Lose the Pacific War, and to the winners go the spoils. So, to Soviet Russia went the return of Sakhalin Island. The Kuriles has always been a "geopolitical thorn". https://en.wikipedia.org/wiki/Kuril_Islands_dispute Of course. Sakhalin has been very restricted until well after the fall of the Soviet Union, however those restrictions have since been lifted.