Editing Japanese calendar (section)

==History==
[[File:Japanese-Calendar-Color-Woodcut-1867.png|thumb|upright=1.25|Japanese Calendar ([[woodcut]], 1867)]]
<gallery>
File:Briefly_Abridged_Calendar_of_1873%2C_Hiroshige_Museum_of_Art.JPG|Briefly Abridged Calendar of 1873
File:Calendar_for_1907%2C_Nakai_Tokujiro_%28Pub.%29%2C_Hiroshige_Museum_of_Art.JPG|Calendar for 1907
</gallery>

Over the centuries, Japan has used up to four systems for designating years:<ref>Clement, Ernest W. (1902). "[https://books.google.com/books?id=iq8BAAAAMAAJ&pg=PA1&dq= Japanese Calendars]", in ''Transactions of the Asiatic Society of Japan,'' Vol. 30–31, p. 3,</ref> the Chinese [[sexagenary cycle]], the {{nihongo|[[Japanese era name|era name]]|元号|gengō}} system, the [[Japanese imperial year]] ({{nihongo krt||皇紀|kōki}} or {{nihongo krt||紀元|kigen}}) and the {{nihongo|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 calendar|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.<ref name="auto8">See the page on the history of the calendar at the National Diet Library site: [http://www.ndl.go.jp/koyomi/e/].</ref><ref>Bramsen, [https://archive.org/details/bub_gb_mk8aAAAAIAAJ/page/n71 pp. 5–11].</ref> 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., {{nihongo2|己酉}}.

In modern times, the old Chinese calendar is virtually ignored; celebrations of the [[Lunar New Year]] are thus limited to [[Chinese people in Japan|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 {{nihongo|[[Japanese era name|era name]]|元号|gengō}} system was also introduced from China, and has been in continuous use since AD 701.<ref>Bramsen, [https://archive.org/details/bub_gb_mk8aAAAAIAAJ/page/n65 pp. 2–5].</ref> The reigning [[List of Emperors of Japan|Emperor]] chooses the name associated with their [[regnal years|regnal eras]]; before 1868, multiple names were chosen throughout the same emperor's rule, such as to commemorate a major event.<ref name="auto5">See list of nengō with the reasons for the changes in ''Rekishi Dokuhon'', January 2008 ("Nihon no Nengo Tokushuu"), pp. 196–221.</ref> For instance, the [[Emperor Kōmei]]'s reign (1846–1867) was split into seven eras, one of which lasted [[Man'en|only one year]].<ref name="auto5"/> Starting with Kōmei's son the [[Emperor Meiji]] in 1868, there has only been one ''gengō'' per emperor representing their entire reign.

The ''nengō'' system remains in wide use, especially on official documents and government forms.<ref>{{cite web| url=http://www.tofugu.com/2014/07/15/understanding-the-ways-that-japan-tells-time/| title=Understanding The Ways That Japan Tells Time| publisher=Tofugu.com| date=July 15, 2014}}</ref> It is also in general use in private and personal business.

The present era, [[Reiwa]], formally began on 1 May 2019.<ref name="auto4">{{cite web | url=https://thediplomat.com/2019/04/japans-new-imperial-era-is-announced-hesei-ends-reiwa-begins/ | title=Japan's New Imperial Era is Announced: 'Hesei' Ends, 'Reiwa' Begins }}</ref><ref name="auto11">{{cite news | url=https://www.theguardian.com/world/2019/may/01/japan-reiwa-naruhito-emperor | title=Japan welcomes new emperor Naruhito as Reiwa era begins | newspaper=The Guardian | date=May 2019 | last1=McCurry | first1=Justin }}</ref><ref name="auto3">{{cite news
|url=https://www.npr.org/2019/04/01/708648297/new-era-name-reiwa-defines-japan-as-emperor-akihito-prepares-to-abdicate|title=New Era Name 'Reiwa' Defines Japan As Emperor Akihito Prepares To Abdicate|work=NPR
|date=1 April 2019|access-date=8 March 2023|author=Francesca Paris}}</ref>  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.<ref>{{cite web | url=https://english.kyodonews.net/news/2019/04/1cb8c8786917-update1-japan-to-announce-name-of-era-under-new-emperor.html | title=Japan's new era named "Reiwa," 1st from native source }}</ref><ref>{{cite web | url=https://apnews.com/bfb2106efca04461a1dd17675a85f18f | title=New Japan era to be called 'Reiwa,' or pursuing harmony | website=[[Associated Press]] | date=April 20, 2021 }}</ref><ref name="auto3"/> The previous era, [[Heisei]], came to an end on 30 April 2019, after Japan's former emperor, [[Akihito]], abdicated the throne.<ref name="auto4"/><ref name="auto11"/><ref name="auto3"/> Reiwa is the first era name whose characters come from a Japanese root source; prior eras' names were taken from Chinese classic literature.<ref>{{cite news | url=https://www.theguardian.com/world/2019/apr/01/reiwa-how-japans-new-era-name-is-breaking-tradition | title=Reiwa: How Japan's new era name is breaking tradition | newspaper=The Guardian | date=April 2019 | last1=McCurry | first1=Justin }}</ref><ref name="auto4"/><ref>{{cite web | url=https://asia.nikkei.com/Spotlight/Japan-s-Reiwa-era/Japan-unveils-dawn-of-the-Reiwa-era | title=Japan unveils dawn of the 'Reiwa' era }}</ref>

===Japanese Imperial Years (''kōki'' or ''kigen'')===

The [[Japanese imperial year]] ({{nihongo krt||皇紀|kōki}} or {{nihongo krt||紀元|kigen}}) is based on the date of the legendary founding of Japan by [[Emperor Jimmu]] in 660 BC.<ref>Bramsen, [https://archive.org/details/bub_gb_mk8aAAAAIAAJ/page/n19 p. 11].</ref> For instance, 660 BC is counted as ''Kōki'' 1.

It was first used in the official calendar in 1873.<ref>See "2533 years since Jinmu's accession" in the heading [http://www.ndl.go.jp/koyomi/e/history/pic10_2_lar.html] {{Webarchive|url=https://web.archive.org/web/20130122230000/http://www.ndl.go.jp/koyomi/e/history/pic10_2_lar.html|date=January 22, 2013}}"</ref> ''Kōki'' 2600 (1940) was a special year. The [[1940 Summer Olympics]] and [[world expo|Tokyo Expo]] were planned as anniversary events, but were canceled due to the [[Second Sino-Japanese War]]. The Japanese naval [[Mitsubishi A6M Zero|Zero Fighter]] was named after this year. After the [[World War II|Second World War]], the [[USFJ|United States occupied Japan]], and stopped the use of ''kōki'' by officials.<ref name="auto7">"kigen" in ''Kokushi Daijiten'', vol. 4 (Yoshikawa Kôbunkan, 1983).</ref>

Today, ''kōki'' is rarely used, except in some judicial contexts.<ref name="auto7"/> Usage of ''kōki'' dating can be a [[Japanese nationalism|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 year]]s<ref>{{nihongo2|閏年ニ關スル件}} (Japanese Imperial [[Edict]] No. 90, May 11, 1898)</ref> 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&nbsp;1900) is divisible by 4; but 2560 − 660 = 1900, which is evenly divisible by 100 and not by 400, so ''kōki'' 2560 (1900) was not a leap year, just as in most of the rest of the world.

===Gregorian Calendar (''seireki'')===

The {{nihongo|Western [[Common Era]] ([[Anno Domini]])|西暦|seireki}} system, based on the [[solar calendar|solar]] [[Gregorian calendar]], was first introduced in 1873 as part of the Japan's [[Meiji period]] modernization.<ref>Bramsen, [https://archive.org/details/bub_gb_mk8aAAAAIAAJ/page/n33 p. 25].</ref><ref name="auto8"/>

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