Itagasa [痛傘[いたがさ]] is the word used to describe an umbrella plastered with cute 2D girlies - just like an Itasha. The reason I brought this up is because I'm thinking of making some - especially some of these clear see-through ones. My line of Itagasa would be decorated by our Mirai Suenaga - I would use it all the time!
Back in the UK, despite being a rainy country, I never saw clear see-though brolleys but in Japan they are everywhere!
All photos snapped from the following sites.
Here are the vinyl ones.
And here are examples of the cloth ones - some of the cloth ones are foldable too.