Japan Fuji

Sea of clouds while climbing the Mount Fuji

The huts are open during 3-4 months in summer. The rest of the year you are on your own and it's more difficult as Fuji is full of snow.
If you wanna use one of the multiples huts in the open season make sure you book it in advance as they run out of spaces pretty soon. (Some people try to sleep outside of huts but you must be prepared as it can be pretty cold depending in the height)