I know 2 people who spent a year in Japan and they said nothing to me about bad manners. The opposite seems true, they were enamored with the country.The locals who boarded the train along the way, were none too happy about being shoulder to shoulder, with a round eyed occidental.
As for me, I rely on a motto I made up in 1975: Every person I meet has an infinite number of possibilities until they open their mouth and start limiting themselves.