Ohayo, Japan friends!
I have news! All Nippon Airways (ANA), Japan’s largest and 5-Star airline for seven consecutive years, is holding its limited “HELLO BLUE SALE”. The sale will run from 29 Nov to 3 Dec, 2019 and features an addition of free* domestic flight within Japan when purchased with an applicable international ticket.
This means you can make like a Tania and fly to Tokyo to Hokkaido back to Tokyo then to Okinawa and finally to Nagoya! Or something like that. Because that's exactly what I did for my three months in Japan in 2018.