Not sure about ANA, but JAL has "Red Seats" reserved for handicapped passengers in front of the check-in counter where an agent will assist you with check-in. Then a wheelchair attendant will take care of you and push you all the way through immigration and security to your gate. Upon arrival a wheelchair will be ready for you when you deplane. While tipping is taboo in Japan, elsewhere I always give a generous tip in the local currency. Fortunately, I have a traveling companion accompanying to assist if needed.