I'm not familiar with the geographic particulars of Germany, but assuming one part is more rural than the other, I feel like the bustling cities, where exposure is more common, usually cures these things.

I would've been less surprised by my experience if it were in the Japanese country side, but Tokyo is a major international city! I expected it to be a lot like my hometown of MIami, where to be racist or xenophobic would have you exhausted since everybody is from somewhere else!