Don't know where you read that satoshi is from Japan?even if he has a Japanese's origin , he could be living in the USA right now.
Who would have known Satoshi better than Hal Finney?
I was reading Hal's post and found this....
Today, Satoshi's true identity has become a mystery. But at the time, I thought I was dealing with a young man of Japanese ancestry who was very smart and sincere.