Magic ink umbrellas
Rain features quite heavily in brilliant Japanese inventions due to the prevalence of rainstorms in all parts of the country. These umbrellas do the job of keeping the rain off of your head (and the rest of you), but they’re also a bit of fun.
When the rain hits them it reveals pretty patterns, a bit like the invisible ink we all used as kids to write secret messages to each other. It must be fun to wander around in a rainstorm and see different characters appearing on everyone’s umbrellas.