How is Italian food in Japan? Is it similar to Americanized Italian food?
Since I've never been, what is ethnic food like in Japan, can you get Mexican/Indian/Ethiopian/Greek/etc or is it just mostly other Asian countries?
In Tokyo, apparently you can get just about anything.
In Osaka, there it's more common to see other asian cuisines, and some Italian/French as Herr Gundam mentioned. Those two are probably the prevalent euro styles, but I suspect they're heavily adapted to Japan. You can get pizza anywhere, and it's so japanified that it is arguably a different food. Or just "bad pizza." Vietnamese, which is super prevalent on the west coast of America, is largely absent from what I've seen, but I have been in two restaurants, one of which had absolutely miserable pho.
I've never seen a Greek or Ethiopian restaurant here.
I want to believe that mexican food in Japan would be really awesome.
I'd like to believe that too, but it is not so. The first place I tried to eat Mexican food at in Japan, it was a lovely, Mexican-themed environment, a spacious patio under the sun, brick and stucco, Spanish colonial façade everywhere. Then the food arrived. It looked great. A build-your-own taco plate with tortillas, sour cream, etc. WOW! Except, it turned out the meat hadn't been warmed; they thought it was supposed to be room temperature. And it wasn't sour cream, it was whipped cream. No joke.
The only other place I've tried it here, it's expensive and not very good. When I make tacos at home, they're better than this place's tacos. However, there are enchiladas and chile rellenos at El Pancho, so I occasionally indulge. The only thing on the menu worth going for are the yuzu (citron) margaritas.