Wow, you have a lot of experience. I'm sorry I can't be of help, but I'm sure one of the topics around here might can give you an idea. One thing I do know of, is that you need a Visa in order to go there, naturally, and usually, one needs a Bachelor's degree to qualify for the Visa. Of course, there's always the other way, where you get hired through a company, and that company sponsors you and then obtain a Visa that way.
I'm also certain that there's a website you can look at that offers English Teaching jobs, but I can't recall it right off.
You could always try this topic....
http://www.japanforum.com/forum/livi...-jp-2-0-a.html