(Aside: my posting is likely to be very off and on for ages as my real life seems to be taking more than 24 hours a day! So on the board it will be a case of 'not all there' - some may notice no difference!)

Do you mean that you sort of
mentally adopt their cultural mannerisms as well?


I don't think it's mannerisms exactly. It goes deeper than that. But there are some things that are tied into the Japanese language that could be said to be matched in their culture (and incidentally in many cases I think British culture may be closer to Japanese than it is to American, but that's a whole other story!).
For example, the language 'expects' politeness to strangers / members of other groups (cf 'the honourable member for XXX' in British politics, but taken seriously). It 'expects' restraint about self - no need to put in 'I' or 'me' as the subject unless it could be in doubt. So less need to push oneself forward, also possibly more practice at noticing others who do not push for attention?
And it is perfectly acceptable (normal!) Japanese to leave sentences unfinished, or finish with 'but' - there is a whole expectation that people will fill in gaps and make the effort to understand what you meant. This is not vagueness or politeness, this is active listening. I certainly should do more of that in English.

But the point is, Jackie, it's not something I feel I'd need to be 'extra-careful' to ensure I did. It's a change in my internal focus that comes about automatically when I am functioning in that language.

...mindless burble before breakfast. I'll try to think of a really good example on the way to work!