Previously, we (my buddy MS and I) cycled from Tokyo to Kyoto in 3 days (via Nagano and Nagoya). Taking up on a challenge from a friend in Kyoto, we decided to go back to Tokyo from Osaka in 2 days (via Hamamatsu). We cycled about 250km with 2,000m elevation per day. Some stats from Strava:
Osaka -> Hamamatsu: 246km, 1855m elevation, 23.6km/h avg., 72.7km/h max.
Hamamatsu -> Tokyo: 248km, 1747m elevation, 23.6km/h avg., 63.7km/h max.
We could barely walk for the next 2 days. Next trip, we will bike to the Gotemba trail head of Mt. Fuji and then hike from there.