Everybody knows that Japan produces the most technologically advanced toilets in the world. They pretty much do everything except pull up your pants when you're finished. And one of the more pleasant surprises greeting foreign visitors to Japan is the ubiquity and accessibility of public toilets.

But there's one toilet-related matter where Japan is still lacking. When we were looking to buy an apartment in the Tokyo Metropolitan area some years ago, one of our conditions was that the unit have two toilets. We quickly learned that the vast majority of condominiums in Japan only contain one toilet. The exceptions are new luxury condos of more than 100 square meters or so.

Initially, we accepted this truth—after all, most apartments in the U.S. only have one toilet, too. Then, later, when we started looking at previously owned single-family houses, we realized that most also only had one toilet, even when they were two-story homes. Eventually, we gave up looking for older properties and had a house built according to our own design, making sure there were two toilets — one off the bedroom and another in the actual bathroom.