Until 2006, Greenery Day used to be celebrated on April 29, the birthday of former Emperor Showa. The day is dedicated to the environment and nature, because the emperor loved plants and nature. Before being declared Greenery Day, May 4 used to be a national holiday due to a law, which declares a day, that falls between two national holidays, a national holiday.
The present observation of Greenery Day as a national holiday in Japan stems from the celebration of the Emperor Shōwa’s birthday on April 29 every year during the Shōwa era. In 1987, following the accession of the current Emperor Akihito to the Chrysanthemum Throne, the name of the holiday was changed from “Birthday of the Emperor” to “Greenery Day”. Officially, as its name suggests, it is a day to commune with nature and to be thankful for blessings. The day was renamed to “Greenery Day” to acknowledge the controversial wartime emperor’s love for plants without directly mentioning his name. However, in practice it is seen as just another day that expands the Japanese Golden Week vacation.
In 2007, Greenery Day moved to May 4, and April 29 was changed to Shōwa Day in accordance with a 2005 revision of the law pertaining to public holidays. The Shōwa Emperor reigned for 62 years and 2 weeks. On May 3, 1947, he became a symbol of Japan by the new constitution of the country.