[godwine]

Second everything that Samurai said.

You are "fairly" safe to find a good place for Yakitori, Ramen and Tempura. For Ramen you can give the Ramen museum a shot, its in yokohama, not too far from Tokyo

Okonomiyaki will be difficult, its a Kensai dish, so your best bet will be Osaka. There is also a couple of nice Okonomiyaki restaurant in Himeji. You are technically in the center of everything (Tokyo, Osaka), so you have many options

Street food is probably what you want to try, try Yakitori at an authentic diner, also try it from street vendor, they are everywhere, but the easiest to find one will be right outside Yoyogi park, they taste different, which one is better is totally debatable

While you are in Osaka, do take a trip to Kyoto and visit the back street of Gion, thats where you will find some nice authentic Japanese diners, many of them have staff that speak semi-fluent english. Do see if you can find a good traditional kaiseki ryori restaurant, its expensive but a "once in a lifetime experieince"

I would recommend taking approximately ￥20000 with you and just withdraw cash using your bank card. Most postal office and the airport (others suggested banks as well, but I haven't try one myself) will have machines that works internationally with debit card

good luck and have fun, keep us posted of your trip