My main language is english, I actually don't know any vietnamese which makes using this site a little bit difficult, but that's what google translate is for i suppose! I know only a little bit of japanese, but I play japanese visual novels anyway.
I am fluent in English and Japanese. I don't know Vietnamese, but if anyone else knows Japanese, that seems like it would be useful as middle-man language for communication considering the high rate of "Japanese" answers in the thread's poll.