I haven't eaten too much Japanese food, but I can agree with the past statments about your body rejecting foods you're not used to. I'm not sure how Japanese food would affect me, but I'm assuming that it wouldn't be too bad. I eat lots of rice and fish as it is, and I'm sure that's primarily what most Asians eat on a daily basis. Correct me if I'm wrong.
As for other folk, if you're eating nothin' but fat burgers, then yeah, you might puke Japanese food. LOL.