,
Chief Cabinet Secretary, announces the name of the new era "
Heisei" (), on 7 January 1989. ,
Chief Cabinet Secretary, announces the name of the new era "
Reiwa" () at the
Prime Minister's Official Residence, on 1 April 2019. , which used the
Jōkyō calendar procedure, published by
Ise Grand Shrine The system on which the Japanese era names are based originated in China in 140 BCE, and was adopted by Japan in 645 CE, during the reign of
Emperor Kōtoku. The first era name to be assigned was , celebrating the political and organizational changes which were to flow from the great of 645. Although the regular practice of proclaiming successive era names was interrupted in the late seventh century, it was permanently re-adopted in 701 during the reign of Emperor Monmu (697–707). Since then, era names have been used continuously up through the present day.
Historical nengō Prior to the
Meiji period, era names were decided by court officials and were subjected to frequent change. A new era name was usually proclaimed within a year or two after the ascension of a new emperor. A new era name was also often designated on the first, fifth and 58th years of the
sexagenary cycle, because they were inauspicious years in
Onmyōdō. These three years are respectively known as
kakurei,
kakuun, and
kakumei, and collectively known as
sankaku. Era names were also changed due to other felicitous events or natural disasters. In historical practice, starts whenever the emperor chooses; and the first year continues until the next lunar new year, which is understood to be the start of the nengō's second year. Era names indicate the various reasons for their adoption. For instance, the nengō , during the Nara period, was declared due to the discovery of copper deposits in
Chichibu ( meaning "Japan", and meaning "copper"). Most nengō are composed of two
kanji, except for a short time during the
Nara period when four-kanji names were sometimes adopted to follow the Chinese trend. , , and are some famous nengō names that use four characters. Since the
Heian period,
Confucian thoughts and ideas have been reflected in era names, such as , and . Although there currently exist a total of 248 Japanese era names, only 73 kanji have been used in composing them. Out of these 73 kanji, 31 of them have been used only once, while the rest have been used repeatedly in different combinations. The vast majority of Japanese era names were used for less than 10 years, with two being used for less than a year. Only 28 have been used for more than 10 years and less than 30 years. Only Heisei, Ōei, Meiji, and Shōwa have been used for more than 30 years.
Nengō in modern Japan Mutsuhito assumed the throne in 1867, during the third year of the era. On 23 October 1868, the era name was changed to , and a system was adopted, wherein era names would change only upon immediate imperial succession. This system is similar to the now-defunct Chinese system used since the days of the
Ming dynasty, in which the era name was not updated until the year following the emperor's death. In modern practice, starts immediately upon the emperor's accession and ends on 31 December. Subsequent years follow the
Gregorian calendar. For example, the Meiji era lasted until 30 July 1912, when the Emperor died and the era was proclaimed. 1912 is therefore known as both "Meiji 45" and , although Meiji technically ended on 30 July with Mutsuhito's death. This practice, implemented successfully since the days of Meiji but never formalized, became law in 1979 with the passage of the . Thus, since 1868, there have only been five era names assigned: Meiji, Taishō, Shōwa, Heisei, and Reiwa, each corresponding with the rule of only one emperor. Upon death, the emperor is thereafter referred to by the era of his reign. For example, Mutsuhito is posthumously known as . It is protocol in Japan that the reigning emperor be referred to as or . To call the current emperor by the current era name, i.e. "Reiwa", even in English, is a faux pas, as this will be his
posthumous name. Use of the emperor's given name (i.e., "Naruhito") is rare, and is considered vulgar behaviour in Japanese. ==Periods without era names==