Japan’s largest mountain park with Hokkaido’s highest mountain Asahidake and an active volcano Tokachi
5±1 day demanding hike (hardcore variant to avoid having tent)
Typically a longer hike (from Asahi-dake Onsen) is made, and it's worth it if you have time.
And one more day is needed to sleep between Hisago-numa goya – Biei Fuji Hnina-goya in a tent.
I took an "express" shorter alternative to manage it in 4 days while staring at evening (60 km, 3800 m up to 2157 m) by merging these two days into one to avoid carrying the tent, but it was an extreme.