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Japanese calendar

Calendars used in Japan past and present

  • 15 min read
  • 4 chapters

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For example, February 16, 2003, can be written as either 2003年2月16日 or 平成15年2月16日 (the latter following the regnal year system). 年 reads nen and means "year", 月 reads gatsu and means "month", and finally 日 (usually) reads nichi (its pronunciation depends on the number that precedes it, see below) and means "day".

Prior to the introduction of the Gregorian calendar in 1873, the reference calendar was based on the lunisolar Chinese calendar.

History

Over the centuries, Japan has used up to four systems for designating years: the Chinese sexagenary cycle, the era name (元号, gengō) system, the Japanese imperial year (皇紀 (kōki) or 紀元 (kigen)) and the Western Common Era (Anno Domini) (西暦, seireki) system. In the 21st century, however, the era system (gengō) and Western system (seireki) are the only ones still widely used.

Chinese calendar

The lunisolar Chinese calendar was introduced to Japan via Korea in the middle of the sixth century. After that, Japan calculated its calendar using various Chinese calendar procedures, and from 1685, using Japanese variations of the Chinese procedures. Its sexagenary cycle was often used together with era names, as in the 1729 Ise calendar shown above, which is for "the 14th year of Kyōhō, tsuchi-no-to no tori", i.e., 己酉.

In modern times, the old Chinese calendar is virtually ignored; celebrations of the Lunar New Year are thus limited to Chinese and other Asian immigrant communities. However, its influence can still be felt in the idea of "lucky and unlucky days" (described below), the traditional meanings behind the name of each month, and other features of modern Japanese calendars.

Era names (gengō)

The era name (元号, gengō) system was also introduced from China, and has been in continuous use since AD 701. The reigning Emperor chooses the name associated with their regnal eras; before 1868, multiple names were chosen throughout the same emperor's rule, such as to commemorate a major event. For instance, the Emperor Kōmei's reign (1846–1867) was split into seven eras, one of which lasted only one year. Starting with Kōmei's son the Emperor Meiji in 1868, there has only been one gengō per emperor representing their entire reign.

The gengō system remains in wide use, especially on official documents and government forms. It is also in general use in private and personal business.

The present era, Reiwa, formally began on 1 May 2019. The name of the new era was announced by the Japanese government on 1 April 2019, a month prior to Naruhito's accession to the throne. The previous era, Heisei, came to an end on 30 April 2019, after Japan's former emperor, Akihito, abdicated the throne. Reiwa is the first era name whose characters come from a Japanese root source; prior eras' names were taken from Chinese classic literature.

Japanese imperial years (kōki or kigen)

The Japanese imperial year (皇紀 (kōki) or 紀元 (kigen)) is based on the date of the legendary founding of Japan by Emperor Jimmu in 660 BC. For instance, 660 BC is counted as Kōki 1. It was first used in the official calendar in 1873. Kōki 2600 (1940) was a special year. The 1940 Summer Olympics and Tokyo Expo were planned as anniversary events, but were canceled due to the Second Sino-Japanese War. The Japanese naval Zero Fighter was named after this year. After the Second World War, the United States occupied Japan, and stopped the use of kōki by officials.

Today, kōki is rarely used, except in some judicial contexts. Usage of kōki dating can be a nationalist signal, pointing out that the history of Japan's imperial family is longer than that of Christianity, the basis of the Anno Domini (AD) system.

The 1898 law determining the placement of leap years is officially based on the kōki years, using a formula that is effectively equivalent to that of the Gregorian calendar: if the kōki year number is evenly divisible by four, it is a leap year, unless the number minus 660 is evenly divisible by 100 and not by 400. Thus, for example, the year Kōki 2560 (AD 1900) is divisible by 4; but 2560 − 660 = 1900, which is evenly divisible by 100 and not by 400, so kōki 2560 was not a leap year, just as in most of the rest of the world.

Gregorian calendar (seireki)

The Western Common Era (Anno Domini) (西暦, seireki) system, based on the solar Gregorian calendar, was first introduced in 1873 as part of the Japan's Meiji period modernization.

Nowadays, Japanese people know it as well as the regnal eras.

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