Last month, the manager of Airbnb Japan told Bloomberg News that Japan is the accommodation service's fastest-growing market, and that he hoped to work with local governments to make regulations more amenable to Airbnb's concept of property owners renting out residences to visitors.

Although the number of travelers using the service in Japan increased in the past year by more than 500 percent, and the number of listings by more than 370 percent, Japan is still behind other countries where Airbnb is available, with only 21,000 rooms listed. Consequently the service, which allows members to connect directly with people who want to let rooms on a short-term basis, is seen as being a possible solution to two ongoing problems in Japan: the shortage of hotel rooms in the face of a startling rise in foreign tourist numbers, and the steady increase in vacant houses and apartments.

The trouble is that the shortage of accommodations is mainly in large cities where vacant housing isn't as prevalent as it is elsewhere in Japan. If you look up some of those 21,000 Japanese properties currently listed on Airbnb, many are in places that few tourists visit.