This video shows you the full Japan Airlines JAL Domestic First Class experience include Lounge to seating to service and food. Pay just 8000 Yen ($70) on the day of departure at the airport for an upgrade from Economy to First Class on Japan Airlines Domestic Flight. I've recently got upgraded from Sapporo to Tokyo on Japan Airlines flight.

This video also show you how to just pay 1,000 yen ($9) to be upgraded from Economy to Business Class on Japan Airlines domestic flight!