The Emperor's Birthday (天皇誕生日, Tennō tanjōbi^?) is a national holiday in the Japanese calendar. It is currently celebrated on 23 December. The date is determined by the reigning Emperor's birthdate.^[1]Emperor Akihito was born on this date in 1933.^[2]

During the reign of Hirohito (Showa period, 1926–1989), the Emperor's birthday was observed on 29 April.^[3] That date remained a public holiday, posthumously renamed Greenery Day in 1989 and Showa Day in 2007.^[4]