This illustration is a Karakasa Kozo, which is a Yokai in Japanese folklore, often depicted as an old paper umbrella that gains its soul after 100 years of use.

The Kanji in the right corner says or Ame futte ji katamaru. means rainfall and means foundation. So literally, this proverb means that constant rainfall strengthens the foundation. In other words, adversity (rainfall) will strengthen ones character (foundation).