The Emperor's Birthday

The Emperor's Birthday
Emperor Akihito prepares to greet the flag-waving crowd at the Imperial Palace on his birthday in 2004.
Official name	Tennō tanjōbi (天皇誕生日)
Also called	Tenchōsetsu (天長節)
Observed by	Japan
Type	National, Public
Significance	Marks the birth date of the Emperor of Japan
Celebrations	Public ceremony at the Imperial Palace, royal greetings
Date	23 December

The Emperor's Birthday (天皇誕生日, Tennō tanjōbi^?) is a national holiday in the Japanese calendar celebrated on 23 December of each year. The date is determined by the reigning Emperor's birthdate.Emperor Akihito was born on 23 December 1933.

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

Prior to World War II, it was called Tenchōsetsu (天長節^?), "Tenchō Festival". Tenchōsetsu paralleled Chikyūsetsu (地久節^?), "Chikyū Festival", which referred to the Empress consort's birthday. The two names originate from the Chinese chengyu 天長地久, borrowed during the reign of Emperor Kōnin, meaning "long heaven, lasting earth" and expressed a hope for the longevity of the reigning Emperor. After the war, the new government renamed it to Tennō tanjōbi, in less formal language with a more literal meaning in 1948, when it was established as a holiday by law. Under the law, the National Diet must convene and change the holiday date before the reigning Emperor's birthday becomes a public holiday. Thus, there exists a small chance that the former Emperor's birthday may come before the change can be made.