With extensive help from the cycling community in Japan, I have now created the version 2 (or 3 for some parts) for the journey. I truly feel blessed and appreciate all the help!
Excluding Okinawa, the total distance is up to more than 3,100km and takes 21 days, so I’m afraid some modifications are still needed. I will try to cut out a day by utilizing public tranportation in non-cyclist friendly, heavy traffic roads. I have received many heads up from local riders around Japan, so I will still have to modify the route accordingly.
The average distance per day seems to be around 150km – I know I have the legs for it, but no idea how my body (knees mostly) will last. We will have to wait and see.
As I start, I will post the daily route and Strava link for the actual ride each day.