I don't want to poop on your dream, but a reality check is in order. The problem with what you're saying is, that's pretty much 95% of Asia (unless you have money), and 99% of Japanese (regardless of money). So around 99 out of every 100 Japanese you meet will look down on you or treat you like dirt. It's shitty, but reality. They won't openly show their displeasure at you being among them, they'll just quietly avoid you and ostracize you until you leave on your own, or stare at you like the oddity you are. The kids might be fine with you, but their parents may or may not, and instead demand the company use another teacher for their kid.

Going to another country to work and thinking you won't need to speak any of the local language is very naive of you. Even if you're teaching English, what do you do if the kids don't understand something unless it's explained in terms they already know? To do that, you'll have to speak their language. You might want to invest in Rosetta Stone language software. You might also want to learn all 3 kana syllabaries. Good luck, I guess.