When the first rain drops begin to fall, the entire population of Japan immediately puts up umbrellas. Here, you see a preponderance of clear umbrellas you can see through. Perhaps to be able to see where you are going, or perhaps a way of not feeling quite as claustrophobic in crowded places?
I love to see a little slice of a different culture showing the nuances. Im sure your theory about the clear umberellas is right. I hate using an umberella .... perhaps I need one of these.
I noticed that in your commentary for your rainy Cuban night photo that you enjoy night time street photography. I believe that you have a natural eye for doing wonderfully in that area!