Gengou

Gengō, also written as nengō, is the Japanese era-name system used to designate years in the official calendar. The term literally means “era name.” The system originated in China and was adopted by Japan in the 7th century, becoming the standard method for dating government documents and records. The sequence of era names was established gradually, and the era name changes with the accession of a new emperor, though eras may also end for other auspicious reasons. Each era has a chosen name, typically two kanji, and year numbering restarts at 1 with the beginning of a new era; subsequent years are counted within that era (for example, Reiwa 3).

In modern times, Japan uses both nengō and the Western Gregorian calendar. Nengō remains in use in official contexts, calendars, and some branding, while many daily activities and international communication use the Gregorian year. The current era is Reiwa, which began on May 1, 2019, with the accession of Emperor Naruhito; the preceding era was Heisei (1989–2019). The practice is regulated by government guidelines, and lists of era names and their start dates are maintained by government agencies such as the Agency for Cultural Affairs.

Notes on usage: the nengō system continues to be a formal part of civil administration and public life in Japan, especially in official documents, school calendars, and traditional contexts, even as the Gregorian calendar remains widely used for everyday coordination and international dealings. The interplay between nengō and the Western year is a distinctive feature of Japanese timekeeping.