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Going to teach in Japan would put that on hold and would make it more difficult to find a job if I decided to go back to the US later
Japan isn't much of a short term option.
I know it's unrealistic to go teach in Japan and expect to stay there the rest of your life. Some people do that, of course, but the vast majority teach for a couple of years and then go back home. I'm under the assumption I'd do the same, but if I stayed there a few years I'd then be in my 30's and would be competing for jobs with people who have established careers once I came back to the US.
But who will you be competing with who has lived and worked in Japan? Experience FTW. Just sayin'...