Bike Hugger mentions the popularity of small mini velo bicycles in Japan. These are small wheeled bicycles that may or may not be folders. They include some of the folding bicycles we're familiar with in the U.S. and Europe, but there are many bicycles such as the Bianchi Novita shown here that are made exlusively for the Japanese market. You can see the whole catalog of mini velo Bianchi bicycles at Bianchi's Japan distributor.
There are probably hundreds more models of Nihon-no mini velo jitensha bicycles like these. I've seen a few of these bikes make it here to the United States, where I see them occasionally on Caltrain during my commute in the San Francisco Bay Area.
Like I said Fritz, don't be surprised if some random photographer snaps a pic' of a Masi mini-velo over there in Japan one day. I am looking into developing a series of them for our new Japanese distributor. I promise nothing... but it just might happen.