I was there for over 5 years in total, with a one month holiday separating the first and second years. After that it was 4 years continuous. I was pretty much teaching English the entire time. The way I did things was not ideal, if I could do it all again I would go for some Uni degree first (Japanese language major), get a 3 year working visa and take things easy and see if things fall into place, if not, leave.
Japans a great place in certain aspects, in other aspects it is pretty sad... in my opinion I think in order to be super successful in Japan you have to be fluent in Japanese language and NOT TEACH ENGLISH. The reasons for not teaching English could fill an entire thread, but having said that I know of one successful guy who runs his own English school and is doing great. For the majority of people though, teaching English is something you do to supplement your funds while in Japan, not base your entire stay on it.
I don't want to spam my own thread with more of this stuff, so please everybody else refrain from typing out essays in response and just leave it be. Thanks