Quite a number. But I don't speak Chinese and with my waifu, we blend in very well. I fully agree most of the points will apply if the accent is different, dressing is out of place, etc.
My waifu is from a clan of 600 years. My name is in her family register Koseki Tohon. I am a PR. Honestly, we are in a world of our own. The people we meet are not the sort Nobita described. We don't mix with the average Japanese. Also the police patrol our house often (I'm a kendo volunteer, haha. But also because of her family). As such, our Japanese neighbours look us very up. We are the elite of the Japanese elites.
If I did not marry a Japanese, I will not migrate there even if I had studied since HS. It is a homogeneous population and prejudice against outsiders is prevalent and to me, understandable. I found this common in Korea and China where I had also stayed before.
If not a PR, if not married to a Japanese, if can't speak Japanese fluently. Don't go there to work, migrate or live.
A 4-6 day tourist will do. Zip in and out and retain the positive image of JP mm, onsen, ryokan, sushi, etc.
The stress of being a Japanese or living in Japan for the average is tremendous.