Interesting, interesting question though, you can't get a job here without a visa allowing you to work in Japan and can even stay no longer than a specified period, which depends on your nationality. As a American 90 days is the maximum. http://www.jnto.go.jp/eng/arrange/essential/visa.html Talking about a working visa, it's not the one you apply for but the one your prospective company applies for at the consulate. Around 2000 there were a lot of English conversation schools which were eager to hire English speakers. I actually know some who came to Japan without visa and found a job during the staying period. But now, it's pretty difficult to go for the same unless you have special skills or you are pretty fluent in Japanese. Your best chance is to find a company or someone who employs you while you're in the US. Or you can apply for some programs like JET as the other answerer has already told you. Personally I like people those who are nonchalant, let me say, like you or me. And I won't say it's impossible to obtain a working visa after you come to Japan. But it's too gambling and highly possible that you waste your time and money, then get to hate Japan. If I were you, first I would look for some Japanese people on Craigslist or somewhere in your area, and I'd learn Japanese at the same time as learning how to teach English. One of them might be your prospective employer, right? By the way, the fastest, easiest and most popular way for douchebags is coming and finding the ugliest girl in Japan and getting married to her like a legendary blues guitarist Robert Johnson did. And I hope you are not one of those ;)

I've read your additional question. You don't need to wait for coming back to Japan as long as you leave Japan right before the expiring date, I think (plz, make sure by yourself). So theoretically it's possible like you go to Korea then go back to Japan on the same day. But it all depends on an immigration officer at the airport. If he feels suspicious of you, then your staying period would be shortened from the maximum 90 days. And it's almost impossible for you to stay in Japan after the period unlike in the US. There are thousands of cops to take on. Comparing to us, you're lucky because a demand for English speakers itself exists in Japan. In my opinion, speaking Japanese skill is one of the key to grab opportunities. The ability shows us your passion for Japan. Anyways, when you come to Tokyo, please let me know. I'll buy you some beer right before the expiring date. And I wanna ask you how it goes.

HI,Zagrom, If you like to teach English to Japanese school boys&girls, you should become a assistant language teacher(English ALT) in Japanese school. Please check this website. http://www.jetprogramme.org/