I've noticed that the Japanese tend to have very large umbrellas. So large that people have almost run into me on the street because the have their umbrellas angled forward and so can't see where they're going. (There's also a trend toward clear, transparent umbrellas, which would mitigate this problem.)
But what do you do with your umbrella when you go inside? Well, in some office buildings, you can lock it up (for free):
Alternatively, you can use one of these fantastic contraptions. Basically, you put your umbrella in from the top, and then jerk it back toward you.
The result is an umbrella that is tightly wrapped in a narrow plastic bag. This prevents your wet umbrella from knocking up against anything and getting it wet, and keeps the dripping water inside the bag and not on the floor.