Wait, what? There's absolutely no evidence that "Japan chopped down the last of its trees". Why would you say such a thing? You enjoy lying on the internet?
It appears that about 12.5% of Japan's land area is old-growth forest. [1] However, I believe it is also true that there was a fair amount of deforestation in the WWII period, and that today, the majority of the forest is modified or plantations.