Concept
The Japanese era name, also known as gengō, is the first of the two elements that identify years in the Japanese era calendar scheme. The second element is a number which indicates the year number within the era (with the first year being "gan"), followed by the literal "nen" meaning "year". Era names originated in 140 BCE in China, during the reign of the Emperor Wu of Han. As elsewhere in East Asia, the use of era names was originally derived from Chinese imperial practice, although the Japanese system is independent of the Chinese, Korean, and Vietnamese era-naming systems. Unlike these other similar systems, Japanese era names are still in use. Government offices usually require era names and years for official papers. The five era names used since the end of the Edo period in 1868 can be abbreviated by taking the first letter of their romanized names. For example, S55 means Shōwa 55 (i.e. 1980), and H22 stands for Heisei 22 (2010). At 62 years and 2 weeks, Shōwa is the longest era to date. The current era is Reiwa, which began on 1 May 2019, following the 31st (and final) year of the Heisei era. While the Heisei era started on the day after the death of the Emperor Hirohito (8 January 1989), the Reiwa era began the day after the planned and voluntary abdication of the 125th Emperor Akihito. Emperor Akihito received special one-time permission to abdicate, rather than serving in his role until his death, as is the rule. His elder son, Naruhito, ascended to the throne as the 126th Emperor of Japan on 1 May 2019. The system on which the Japanese era names are based originated in China in 140 BC, and was adopted by Japan in 645 AD, during the reign of Emperor Kōtoku. The first era name to be assigned was "Taika", celebrating the political and organizational changes which were to flow from the great Taika reform 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).