[Jedi Master Pikachu]

So Japan had all the Kurils up to the Kamkatcha Peninsula?

And for World War 2, if Japan had attacked the Russians, Russia would have been in a pincer between Japan and Germany. Also, Japan would have been able to take sparsely populated land with lots of resources.

[Vigilanteman]

Yep. The only battle the Russians fought for the Kuriles was on Shumshu, in the northern end of the chain. There was actually a faction within the Japanese government that advocated attacking Russia and leaving America out of the war. The advantages, as you pointed out, would be lots of territory and minimal resistance. The disadvantage would be massive infrastructure needed to develop the oil fields.

History would have turned out entirely differently had Admiral Yamamoto's viewpoint prevailed over General Tojo's.