Had a Japan Rail pass that was expiring at midnight, however had a 11am train.
Caught the 11:30pm train to Narita and decided to bunker down for the night.
Got rounded up with about 12 others and we slept in this little waiting room near the checkin counters under supervision of police.
They took all ID's and informed that we were not allowed to be homeless in Japan (ID check happened about 4 times before they let us sleep), then got woken up by some people from the US army base who assumed I was one of the ones they lost and needed to take to the base (some others got delayed and missed the earlier pickup).