Please understand that there are 3 kinds of accommodation in Shirakawago, like minshuku, ryokan or hotel.
Accommodation information: http://www.shirakawa-go.gr.jp/search/?m=1
If you want to stay Ryokan or Hotel type, please directly contact below address.
info-e@shirakawa-go.gr.jp

In order to understand what's Gassho house, please see below explanation carefully.

A. Gassho house (a traditional Japanese farm house)
Budget per person/night: 8.500 yen to 12.000 yen
Bathroom in each room: no
Rooms are separated by paper doors. No locks, no keys.
Number of rooms: 3 ~ 5 rooms
Meals: Japanese
Hot spring: no

B. Ryokan (a traditional Japanese hotel)
Budget per person/night: 10.000 yen to 25.000 yen
Bathroom in each room: yes/no
Rooms are separated by walls
Number of rooms: 5 ~ 17 rooms
Meals: Japanese
Hot spring: yes/no

C. Hotel (a western style hotel)
Budget per person/night: 11.000 ~
Bathroom in each room: yes/no
Rooms are separated by walls
Number of rooms: 31 rooms
Meals: French
Hot spring: yes