The Emperor's Birthday is a national holiday in the Japanese calendar celebrated on the birthday of the reigning Emperor, which is currently 23 February, as Emperor Naruhito was born on that day in 1960. Emperor Emeritus Akihito, whose birthday is 23 December, abdicated the throne on 30 April 2019, meaning that the holiday was not observed in 2019, and that the holiday was moved to Emperor Naruhito's birthday the following year. During the reign of Emperor Hirohito, 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, "Tenchō Festival". Tenchōsetsu paralleled Chikyūsetsu, "Chikyū Festival", which referred to the Empress consort's birthday. The two names originate from the Chinese idiom 天長地久, borrowed from Lao Tzu's Tao Te Ching during the reign of Emperor Kōnin, meaning "The sky and the earth, the universe is eternal", and expressed a hope for the eternal 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. On the Emperor's birthday, a public ceremony takes place at the Imperial Palace, where the gates of the palace are opened to public traffic. The Emperor, accompanied by the Empress, and several other members of the imperial family appear on a palace balcony to acknowledge the birthday congratulations of crowds of festive well-wishers waving tiny Japanese flags. Only on this occasion and for the New Year celebration on 2 January may the general public enter the inner grounds of the Imperial Palace. When the Emperor ceases his greeting, the crowd starts waving the flags again and the Imperial Family waves back.
