I am considering the following itinerary departing in about a week:
LAX-NRT on NH in J (booked through VS)
connecting same day to:
NRT-SIN-DPS on SQ in Y (booked through UA)
I cannot enter Japan so I'm wondering if I should anticipate any problem with NH 1) allowing me to board at LAX, and 2) checking my baggage through to DPS. I will arrive very early to deal with any problems.