Forget about what his wiki page is saying or whatever we have read about him. Reading through Satoshi's post on this forum, anyone with common sense and good understanding of English language could see clearly that the Bitcoin founder is by no means a Japanese. I spent the whole day reading through them, and here are some outstanding posts he made prior to his disappearance. The perfect use of English is telling and undeniable.
"Perfect use of English" does not exclude people for whom English is a second language. For example, the great writer Vladimir Nabokov is native to Russia, but I find that his command of the English language is better than most native English speakers.
I agree that some people can write texts in English that is indistinguishable from that of native speakers. Not to mention that some native speakers can be so bad at writing that one might assume that English is their second language... And while the op asks us to forget the stuff from Wikipedia, I'd like to point out a fair argument available there, regarding the time zone.
Stefan Thomas, a Swiss coder and active community member, graphed the time stamps for each of Nakamoto's bitcoin forum posts (more than 500); the resulting chart showed a steep decline to almost no posts between the hours of 5 a.m. and 11 a.m. Greenwich Mean Time. This was between 2 p.m. and 8 p.m. Japanese time, suggesting an unusual sleep pattern for someone presumably living in Japan. As this pattern held true even on Saturdays and Sundays, it suggested that Nakamoto was asleep at this time.[8]
Surely, a Japanese guy can live in Europe, but I think that it makes it unlikely that the person we call Satoshi lived in Japan in 2009 and 2010. I think there's a good chance it's someone from Britain, though.