I know the basic use of the phrase 国に帰る. What I’d like to know is when a Japanese person uses this phrase, do they (without giving it much thought, perhaps) imply that a foreigner is always to come back to their country of origin?
Let’s imagine a person who’s lived in Japan for many years and for who the country has become home, so there is no other country return to - they are where they are supposed to be. Will the same old 国に帰る be used?
Basically yes, 国に帰る can be used in such a situation.
国（くに) in the expression is sometimes written as 故郷 (with the pronunciation くに), homeland. So 国に帰る can be used as long as the speaker perceives it as his/her homeland.
As such in some cases 国に帰る may not be used or can be ambiguous - if A was born in the US and moved to Japan at the age of three, then A wouldn't seriously say 国に帰る to mean going to the US. Or if a 50-year-old American person B has lived in Japan for thirty years and he says 国に帰る somewhere outside Japan and the US, then it can be ambiguous - going to Japan or to the US (To me it sounds more like to the US, though).
Added If a Japanese says 国に帰る, then usually it means going back to his/her hometown for a long term/permanently.
