If you're a tourist visiting Japan, then odds are you're going to notice that there always seem to be clothes that are out and hung to dry. That's because people do laundry every day in Japan. It's considered unclean to wear a piece of clothing more than once without washing it. The same is true of some items in the West, but not to the degree it is in Japan.
Clothes dryers are also not as common in Japan as they are in some countries in the West, so expect to see a lot of laundry lines when visiting Japan.