I did not know JL/NH did that. JL/NH operated two types of domestic flights out of NRT. One was pure domestic flight, could purchase domestic only could fly as domestic passengers. Any international connecting passengers on this flight cleared passport control and customs at NRT.

Another was international connection flight which was treated as international flight. Only international passengers were allowed on these flights and passengers did not clear customs and passport control at NRT, but did those formalities at the destination such as KIX. However, I did not know that connecting international passengers cleared customs and passport control at NRT could fly on this flights.

JL and NH used to have those international connecting flights just few years ago, because I took them but looks like they do not have international connecting flights now.

Thanks for the info.