The funny thing is that while western style toilets were very much a novelty in 1983 when I was there, the Japanese have since taken the concept and run with it. Japanese toilets are now incredibly high tech, with seat warmers, build in bidets, lights, music, and about 20 different settings, to do who knows what! My brother has one in his home in California, and it's always an adventure to use it. Not that you will find them in everyday people's homes, since they are expensive, but the western style toilet has definitely taken over in Japan.
And yes, if I were to go back to Japan, as a 70