Japanese calendar types have included a range of official and unofficial systems. At present, Japan uses the Gregorian calendar together with year designations stating the year of the reign of the current Emperor."Calendar" at Japan-guide.com; Bramsen, William. (1880). Japanese chronological tables, p. 25. The written form starts with the year, then the month and finally the day, coinciding with the ISO 8601 standard.
For example, February 16, 2003, can be written as either or (the latter following the regnal year system). reads and means "year", reads and means "month", and finally (usually) reads (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:Clement, Ernest W. (1902). "Japanese Calendars", in Transactions of the Asiatic Society of Japan, Vol. 30–31, p. 3, the Chinese sexagenary cycle, the system, the Japanese imperial year ( or ) and the system. In the 21st century, however, the era system () and Western system () 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.See the page on the history of the calendar at the National Diet Library site: .Bramsen, pp. 5–11. 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., .
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 ()
The system was also introduced from China, and has been in continuous use since AD 701.Bramsen, pp. 2–5. 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.See list of nengō with the reasons for the changes in , January 2008 ("Nihon no Nengo Tokushuu"), pp. 196–221. 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 per emperor representing their entire reign.
The 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 ( or )
The Japanese imperial year ( or ) is based on the date of the legendary founding of Japan by Emperor Jimmu in 660 BC.Bramsen, p. 11. For instance, 660 BC is counted as 1. It was first used in the official calendar in 1873.See "2533 years since Jinmu's accession" in the heading " 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 by officials."kigen" in Kokushi Daijiten, vol. 4 (Yoshikawa Kôbunkan, 1983).
Today, is rarely used, except in some judicial contexts. Usage of 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 (Japanese Imperial Edict No. 90, May 11, 1898) is officially based on the years, using a formula that is effectively equivalent to that of the Gregorian calendar: if the 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 2560 (AD 1900) is divisible by 4; but 2560 − 660 = 1900, which is evenly divisible by 100 and not by 400, so 2560 was not a leap year, just as in most of the rest of the world.
Gregorian calendar ()
The system, based on the solar Gregorian calendar, was first introduced in 1873 as part of the Japan's Meiji period modernization.Bramsen, p. 25.
Nowadays, Japanese people know it as well as the regnal eras.
Divisions of time
Seasons
There are four seasons corresponding to the West's. Unlike those, they traditionally do not begin with an equinox or a solstice but have it roughly in their center, so they begin six to seven weeks earlier than their European counterparts:
+ 4 astronomic seasons English name Japanese name Romanization Traditional dates Length Spring February 5 – May 6 92 Summer May 7 – August 8 94 Fall August 9 – November 7 91 Winter November 8 – February 4 89
Solar terms and micro-seasons
There is also a traditional system of , consisting of each divided into three sets of five days, and with specially-named days or indicating the start and end of each.
This system was adapted from the Chinese in 1685 by court astronomer Shibukawa Shunkai, rewriting the names to better match the local climate and nature in his native Japan. Each kō has traditional customs, festivals, foods, flowers and birds associated with it:
The kō have also been referred to as 5-day weeks, although some may be 6 days or even just 4 days long.
+ 24 solar terms (sekki) divided into 72 micro-seasons (kō) Solar term Kō number Traditional dates Length Japanese name Romanization Translation 01February 4–85The east wind melts the thick ice.02February 9–135Bush warblers sing in the countryside.03February 14–185Ice cracks, allowing fish to emerge. 04February 19–235Rain falls, moistening the soil.05February 24–285+Mist lies over the land.06March 1–55Trees and plants put forth buds. 07March 6–105Hibernating insects emerge.08March 11–155Peach trees begin to bloom.09March 16–205Cabbage whites emerge from their cocoons. 10March 21–255Sparrows begin building their nests.11March 26–305Cherry blossoms begin to bloom.12March 31 – April 45Thunder rumbles far away. 13April 5–95Swallows return from the south.14April 10–145Wild geese fly north.15April 15–195Rainbows begin to appear. 16April 20–245Reeds begin to sprout.17April 25–295Rice seedlings grow.18April 30 – May 45Peonies bloom. 19May 5–95Frogs begin croaking.20May 10–145Worms wriggle to the surface.21May 15–206Bamboo shoots sprout. 22May 21–255Silkworms feast on mulberry leaves.23May 26–305Safflowers bloom in abundance.24May 31 – June 56Barley ripens, ready to be harvested. 25June 6–105Praying mantises hatch and come forth.26June 11–155Fireflies fly out from moist grass.27June 16–205Plums ripen, turning yellow. 28June 21–266Prunella flowers wither.29June 27 – July 15Irises bloom.30July 2–65Crowdipper sprouts. 31July 7–115Warm winds blow.32July 12–165Lotuses begin to bloom.33July 17–226Young hawks learn to fly. 34July 23–286Paulownia trees begin to produce seeds.35July 29 – August 25The ground is damp, the air hot and humid.36August 3–75Heavy rains fall. 37August 8–125Cool winds blow.38August 13–175Evening cicadas begin to sing.39August 18–225Thick fog blankets the land. 40August 23–275Cotton bolls open.41August 28 – September 15The heat finally relents.42September 2–76Rice ripens. 43September 8–125White dew shimmers on the grass.44September 13–175Wagtails begin to sing.45September 18–225Swallows return to the south. 46September 23–275Thunder comes to an end.47September 28 – October 25Insects close up their burrows.48October 3–75Fields are drained of water. 49October 8–125Wild geese begin to fly back.50October 13–175Chrysanthemums bloom.51October 18–225Crickets chirp by the door. 52October 23–275Frost begins to form.53October 28 – November 15Drizzling rain falls gently.54November 2–65Maple leaves and ivy turn yellow. 55November 7–115Sasanqua camellias begin to bloom.56November 12–165The land begins to freeze.57November 17–215Daffodils bloom. 58November 22–265Rainbows disappear.59November 27 – December 15The north wind blows leaves off the trees.60December 2–65Tachibana citrus trees begin to turn yellow. 61December 7–115The skies stay cold as winter arrives.62December 12–165Bears hide away in their dens to hibernate.63December 17–215Salmon swim upstream en masse. 64December 22–265Prunella sprouts.65December 27–315Deer shed their antlers.66January 1–44Barley sprouts under the snow. 67January 5–95Parsley thrives.68January 10–145Springs once frozen flow once more.69January 15–195Cock pheasants begin to call. 70January 20–245Butterburs put forth buds.71January 25–295Mountain streams gain a cover of thick ice.72January 30 – February 35Hens begin to lay eggs.
Zassetsu is a collective term for special seasonal days within the 24 sekki.
+ Zassetsu holidays Date Kanji Romaji Comment February 3 the eve of Risshun by one definition March 18 – March 24 the seven days surrounding the start of Shunbun c. March 21, vernal equinox day in Shinto in Buddhism May 2 literally meaning 88 nights (since Risshun) June 11 literally meaning entering tsuyu July 2 farmers take five days off in some regions July 15 officially July 15, but August 15 in many regions (Tsuki-okure) July 20 custom of eating eel on this day September 1 literally meaning 210 days (since Risshun) September 11 literally meaning 220 days September 20 – September 26 the seven days surrounding the start of Shūbun c. September 23, Autumn equinox in Shinto in Buddhism
Shanichi dates can vary by as much as 5 days. Chūgen has a fixed day. All other days can vary by one day.
Many zassetsu days occur in multiple seasons: refers to the 18 days before each season, especially the one before fall which is known as the hottest period of a year. is the seven middle days of spring and autumn, with Shunbun at the middle of the seven days for spring, Shūbun for fall. is the day closest to Shunbun (middle of spring) or Shūbun (middle of fall), which can be as much as 5 days before to 4 days after Shunbun/Shūbun.
The term originally referred to the eves of , , , and ; however, it now only refers to the day before .
Months
As mentioned above, the Japanese calendar was previously based on an adaptation of the Chinese lunisolar calendar, which begins 3 to 7 weeks later than the Gregorian. In other words, the Gregorian "first month" and the Chinese "first month" do not align, which is important in historical contexts.
The "traditional names" for each month, shown below, are still used by some in fields such as poetry; of the twelve, is still widely used today. The opening paragraph of a letter or the greeting in a speech might borrow one of these names to convey a sense of the season. Some, such as and , do double duty as given names (for women). These month names also appear from time to time on , contemporary television shows and movies set in the Edo period or earlier.
The Japanese names for the modern Gregorian months literally translate to "first month", "second month", and so on. The corresponding number is combined with the suffix . The table below uses traditional numerals, but the use of Western numerals (, , , etc.) is common.