August 1st "Water Day"

It is an anniversary set by the government as a day to think about the importance of water and the healthy water cycle. Every year, various events and landmarks are lit up in blue. This yearBlue light-up carried out at 52 locations nationwide. Carry the Sun, with the cooperation of Prince Hotels, colored Shiba Park in bright blue.

https://www.mlit.go.jp/mizukokudo/mizsei/mizukokudo_mizsei_tk1_000080.html