Ahh Himeji. There’s not much to this town aside from a BEAUTIFUL castle. (And an equally stunning little garden next to said castle … I bet not many of you knew that but it is definitely worth seeing.) So I was more than a little surprised to see … birds … on their manhole cover.
And then I went home and looked it up. As it turns out, the birds that grace Himeji’s street covers are white herons … which also happens to be the same moniker that Himeji Castle goes by due to its snowy exterior. So in the end, Himeji’s city council was pretty clever in their street design.
Uncover Japan 
That was interesting. At first glance, I believed they were “tsuru”. What does “osui” mean at the bottom?
“Sui” is another reading of the kanji for water so as far as I know, “osui” is just another term for water, perhaps specific to sewers.
It is a great idea and makes perfect sense as the castle is also known as Shirasagi-jō (“White Heron Castle”) due to its white exterior.