Two things:
1. I think chryuop has a very good and accurate definitino of "fluent." I see that word bandied about by conversational speakers as if they were fluent all the time. Fluency to me is the ability to almost always say
exactly what you want to say without editing to avoid phraseology you don't know, but you don't have to have the native accent.
The third alternative to chryuop's ways to attain and maintain fluency is to get a job at a Japanese embassy in your country. I have a friend who did this. I haven't heard her speak Japanese in a while, but it was very, very good. I could sense no hesitation on her part. She may not have been fluent, but she was pretty damn close—closer than I in any case.
2. We all know the oldest dialect of Japanese is Korean, guys. Stop fighting.
