Originally Posted by
Steve M
My understanding is that much like arriving US Immigration, foreign nationals that have permanent residency in Japan (that is, gaijin card with re-entry permit) are allowed to use the Japanese National lines. All others are to use the Visitors line without respect to who they're with. Well, actually there's a third line at some airports for sangokujin (aka "special permanent residents") but you'd probably already know if this applied to you.
If you have a re-entry permit you use the re-entry permit line (doesn't matter if you are PR or not as you can have a re-entry permit but not be a Permanent Resident like me), often times then not the re-entry permit line is faster then the Japanese National line and regular lines. Often times there will be few re-entry permit holders (from my observation when arriving) that they just start letting regular people use the re-entry permit line as well, it is quite fast, faster then the Japanese line in my opinion.
As for separation, I can't see any reason why "not" a Japanese person can use the non-japanese or re-entry line, they just don't do the fingerprint/photo section.