Originally Posted by
seigex
check up a few posts, I posted an account from someone on reddit who was allowed to board even though they had a NRT/HND transfer. YMMV of course.
Mistakenly allowed to board, I am sure that the airline was fined for bringing in a passenger on an impossible connection. Somewhat lucky that Japan sometimes can be pragmatic. There are also cases of people who have overnighted in Narita due to missed connections.
It does not mean you should plan for it.