Originally Posted by
dvo1029
I agree that I would likely be denied boarding because I have an immediate return flight booked on UA back to EWR. However, if I truly was transiting, for example my original plan to Manila, then I assume UA would not have denied boarding since I would be transiting to a third county,
Agents at airport don't have the information of your immediate turnaround, so as far as they are concerned, your final destination is bound for Tokyo.
While adding an additional onward destination would qualify you for transit, Manilla is closed to foreigners (as you had alluded to in your original post), so you would have a similar fate with a EWR-NRT-MNL ticket when boarding at EWR.