by yamachem - uploaded on July 6, 2015, 1:36 am
The image is a blackboard, on which a Japanese onomatopoeia called "ざあざあ" in hiragana or "zaazaa" is depicted.
This onomatopoeia is used in the situation when it's rainning cats and dogs.
There is a good website for learning Japanese language, particularly Japanese onomatopoeia.
For it, see my below comment.