I have an business-class JAL ticket HAN-NRT, NRT-BOS with open-jaw in Tokyo for next month. Long story short, I'm no longer going to be in Vietnam, but want to use this ticket to get back to BOS. Airline will only allow it if I fly both segments.

My plan is to buy a ticket NRT-HAN arriving at 21:50 (booked as AA 8840 codeshare JAL metal), proceed to connecting flights / transfer, security recheck, and board the onward flight HAN-NRT departing at 23:20 (booked as JL 752).

Transit time of 1h30m is tight, but I think possible as HAN is usually not busy at night time in my experience. I do not have Vietnam visa, but I have the onward ticket, just happens to be the same JAL plane I arrived on (the only JAL flight). I will have no checked luggage as that would require post-immigration pickup.

Also, it is NOT a visa-run. My Japanese entry-free is well under the allowed stay. But I wonder if it's a problem to stamp out of Japan, not enter anywhere, and then stamp back into Japan?

I think this plan works, as nutty as it may be, but appreciate any input from you more experienced travelers. Thank you!