Today is Midori no Hi (みどりの日) in Japan, part of a week long string of holidays known as "Golden Week", in which most of the country is given time off from work and take the opportunity to travel or spend time with family.
Midori no hi itself is, as you might expect, a celebration of all things green. Parks and gardens in Tokyo and other cities have events to honor nature and some places plant trees, but all around the country there is a general initiative to clean up parks, beaches, and other areas.
Greenery Day finds its roots in the celebration of the Emperor Showa's birthday on April 29th during the Showa era in Japan (1925-1989). In 1989, the name of the holiday was changed from "Birthday of the Emperor" to "Greenery Day", but was still observed on April 29th. In 2007, Greenery Day was moved to May 4th.
Celebrate Greenery Day wherever you are! Plant a tree, pick up some litter. Have you ever celebrated a holiday like this?