Today is the second of the three holidays that mark Golden Week in Japan. Midori no Hi means Greenery Day and goes back to the Showa emperor who was particularly fond of plants. It is celebrated on May 4th since 2007, between 1989 and 2006 it was celebrated on the Showa emperor’s birthday on April 29th.
The day is also called Arbor Day, and one of the duties of the Emperor and the Empress include planting seeds and a tree somewhere in the countryside of Japan. Unfortunately, I could not find any detailed information where they went this year, but I am sure as from today, there will be a few more trees growing in Japan.