Hotels are already cheap in Japan ($60 a night will get you quite a nice business hotel with hot spring in most places I've been) and Airbnb is subject to local restrictions (federal law passed recently allows local governments to place restrictions on Airbnb - you have to get a permission letter from your city Hall to be allowed to list on airbnb - and they can deny you for any reason eg neighbour complaints). Personal use would be a possibility for sure.