No discussion of Japanese hotel typologies would be complete without a dip in to the work of the Metabolist architects and in particular the work of Kisho Kurokawa. The14 story Nakagin Capsule Tower, one of his most famous works, is now slated for demolition to near universal uproar. It was originally conceived as a hotel for business workers who could not get home late of an evening. It had a surprising level of accommodation that the images reproduced here of a renovated capsule demonstrate.
The idea was taken to a more extreme level with The Capsule Hotel in Osaka. It reduced the sleeping space for guests into something like a large coffin or crawl space with a glass front. It is still a functioning hotel and is now an international tourist attraction in its own right.
Capsule hotels did not really spread beyond Japan but their influence certainly did. Several hotel brands in other countries have tried to reduce the essentials of accommodation from a standard hotel room of around 25m2 into ever smaller packages.
I think its fair to say however that Kurokawa's designs have not been surpassed either for their innovation or design excellence.
Further information:
Wikipedia,
Designboom
Japan Times
Arcspace