Jlit Net

The Japanese calendar


The Five Elements, Ten Stems, and Twelve Branches

The classical Japanese calendar was based on a complex cosmological system imported from China. At the core of this system were the Five Elements (go-gyō) of wood (ki), fire (hi), earth (tsuchi), metal (kin; pronounced "ka" in this system), and water (mizu). Each element was further divided into yang and yin aspects, the former designated by the Chinese character for "elder brother" and pronounced "e," the latter designated by the Chinese character for "younger brother" and pronounced "to." The result was a series of Ten Stems (jikkan). Each stem was given a separate Sinicized name, and these names formed the basis of a style of enumeration that is still used, for instance, in legal contracts and theater seating arrangements. Indeed, most modern Japanese will be able to rattle off the first three or four of these stems with ease, although the rest may well cause trouble.

The following table lists the Ten Stems, showing their derivation from the yang and yin aspects of the Five Elements. The relevant Chinese character may be read in either Japanese or Sinicized fashion; the latter is the form used for enumerative purposes:

Element Japanese reading Chinese character Sinicized reading
Wood (yang) ki-no-e (木の兄)
Wood (yin) ki-no-to (木の弟) otsu
Fire (yang) hi-no-e (火の兄) hei
Fire (yin) hi-no-to (火の弟) tei
Earth (yang) tsuchi-no-e (土の兄) ho
Earth (yin) tsuchi-no-to (土の弟) ki
Metal (yang) ka-no-e(金の兄)
Metal (yin) ka-no-to (金の弟) shin
Water (yang) mizu-no-e (水の兄) jin
Water (yin) mizu-no-to (水の弟) ki

The phases of the moon (getsurei) and names of the months

The traditional Japanese calendar was primarily a lunar calendar, and great attention was paid to the phases of the moon. A month started and ended with the new moon, and a full moon marked the middle of the month. The moon first revealed itself as a crescent with its two tips pointing more or less upward, giving rise to a comparison with a bow with the drawstring at the top (called jōgen no tsuki). As the moon waxed and waned, the arch of the bow moved upward and the moon became a kagen no tsuki, or "moon with the drawstring at the bottom" (in each case, the shape refers to the appearance of the moon at the time it sets).

The following table lists the names that were used to describe the different phases of moon during the course of the month:

Term for the moon Japanese Approx. day of lunar month
Approx. time of moonrise
shingetsu / tsugomori 新月 / つごもり 30th day of the month
6 a.m.
futsuka-zuki 二日月 2nd day of the month
7:30 a.m.
mika-zuki 三日月 3rd day of the month
8:30 a.m.
nanoka-zuki 七日月 7th day of the month
11:30 a.m.
yōka-zuki 八日月 8th day of the month
12:30 p.m.
kokonoka-zuki 九日月 9th day of the month
1:30 p.m.
tōka-amari no tsuki 十日余りの月 11th day of the month
2:30 p.m.
jūsan'ya-zuki / komochi-zuki 十三夜月 13th day of the month
4:30 p.m.
mochi-zuki / mangetsu 望月 / 満月 15th day of the month
6:30 p.m.
izayoi-zuki 十六夜月 16th day of the month
6:30 p.m.
tachimachi-zuki 立ち待ち月 17th day of the month
7 p.m.
imachi-zuki 居待ち月 18th day of the month
8 p.m.
fushimachi-zuki / 
伏し待ち月 / 寝待ち月 19th day of the month
9 p.m. (ariake, or lingering moon, from about this point)
fukemachi-zuki /
更け待ち月 / 二十日月 20th day of the month
10 p.m.
hatsuka-amari no tsuki 二十日余りの月 22nd day of the month
10:30 p.m.
nijūsan'ya-zuki 二十三夜月 23rd day of the month
12:30 a.m.

The names of the months

The months, though often simply called the First Month, the Second Month, and so on, also had a variety of other names. The table below gives the most common traditional names for the 12 lunar months of the year, along with two common variants and the seasons that were associated with each month. For the problem of how synchronization with the solar year was handled, see the next tab.

Season Month Japanese Other names
Spring Mutsuki 睦月 Hatsutsuki (初月), Shōgatsu (正月)
  Kisaragi 如月 Umemizuki (梅見月), Yukigezuki (雪消月)
  Yayoi 弥生 Hanamizuki (花見月), Sakurazuki (桜月)
Summer Uzuki 卯月 Natsuhazuki (夏初月), Hananokoshizuki (花残月)
  Satsuki 皐月 Sakumozuki (さくも月), Tagusaziki (田草月)
  Minazuki 水無月 Kazemachizuki (風待月), Seminohazuki (蝉葉月)
Autumn Fuzuki 文月 Akihazuki (秋初月), Tanabatazuki (七夕月)
  Hazuki 葉月 Katsurazuki (桂月), Kosomezuki (木染月)
  Nagatsuki 長月 Nezamezuki (寝覚月), Momijizuki (紅葉月)
Winter Kannazuki 神無月 Shigurezuki (時雨月), Koharu (小春)
  Shimotsuki 霜月 Yukimizuki (雪見月), Kamigaerizuki (神帰月)
  Shiwasu 師走 Umehatsuzuki (梅初月), Harumachizuki (春待月)

The 24 solar terms (nijūshi sekki)

Solar terms (sekki -- 節気), which mark points 15 degrees apart along the solar elliptic, were used to reconcile the differences that arose between the lunar calendar and the solar year, producing the traditional lunisolar calendar. The winter solstice served as the starting point for making these calculations (the winter solstice was always located in the Eleventh Month). Each month had two points -- a setsu (節)and a chū (中)-- and each point was given a name associated with a particular season. The chū points provided the basis for numbering the sequence of lunar months, thus establishing the connection between the two systems. Intercalary months (urūzuki -- 閏月) were inserted when the discrepancy between the lunar year and the solar year (as reckoned by the sekki system) left a lunar month without a solar chū point, which happened about once every three years. The "empty" month (empty because the lack of a chū point deprived the month of a number in the overall sequence) was given the same number as the preceding month, preceded by the term jun (閏). Thus, jun-nigatsu would be the Intercalary Second Month of the year, following the usual Second Month, and the addition of the extra month would bring the two systems back into alignment. Years with the standard 12 lunar months contained 354 or 355 days, while years with intercalary months were either 383 or 384 days long. It was an extremely complex system.

The following table gives the names of the 24 solar terms, along with their approximate equivalents in the Gregorian system (approximate because the precise date depends upon the year):

Season Solar term
Name Japanese Approximate Gregorian equivalent
Spring shōgatsu-setsu risshun 立春 February 4  (beginning of the year)
  shōgatsu-chū usui 雨水 February 19
  nigatsu-setsu keichitsu 啓蟄 March 6
  nigatsu-chū shunbun 春分 March 21 (spring equinox)
  sangatsu-setsu seimei 清明 April 5
  sangatsu-chū kokuu 穀雨 April 20
Summer shigatsu-setsu rikka 立夏 May 6 (start of summer)
  shigatsu-chū shōman 小満 May 21
  gogatsu-setsu bōshu 芒種 June 6
  gogatsu-chū geshi 夏至 June 21 (summer solstice)
  rokugatsu-setsu shōsho 小暑 July 7
  rokugatsu-chū taisho 大暑 July 23
Autumn shichigatsu-setsu risshū 立秋 August 8 (start of autumn)
  shichigatsu-chū shosho 処暑 August 23
  hachigatsu-setsu hakuro 白露 September 8
  hachigatsu-chū shūbun 秋分 September 23 (autumn equinox)
  kugatsu-setsu kanro 寒露 October 9
  kugatsu-chū sōkō 霜降 October 24
Winter jūgatsu-setsu rittō 立冬 November 8 (start of winter)
  jūgatsu-chū shōsetsu 小雪 November 23
  jūichigatsu-setsu taisetsu 大雪 December 7
  jūichigatsu-chū tōji 冬至 December 22 (winter solstice)
  jūnigatsu-setsu shōkan 小寒 January 6
  jūnigatsu-chū daikan 大寒 January 21

In addition to their role as signs of the zodiac, the Twelve Branches were also used to refer to times of the day and geographical directions. The following graphs illustrate the relationships.

The day was divided into halves, with the two-hour period centered on midnight designated as the Hour of the Rat. When finer distinctions were necessary, these two-hour periods were further divided into quarters (the designation ushi-mitsu would thus refer to the time between 2:00 am and 2:30 am). Another way of calculating time seems to have been based on the importance to divination of multiples of nine, so that the first instance (corresponding to midnight) is kokonotsudoki ("nine of the clock") and a countdown of sorts begins from that point, with two times nine equal to 18, which -- ignoring the leading digit -- yields yatsudoki ("eight of the clock"), three times nine equals 27, and hence 27 --> 7 --> nanatsudoki ("seven of the clock"), and so on, down to yotsudoki ("four of the clock"). There were variations on this system in different historical periods, other terms exist for different ranges of time within the 24-hour day, and in addition there is a theory that holds that the Hour of the Rat actually began at midnight, so that the method indicated by the graph cannot be considered perfectly reliable in all cases.




Each of 12 directions took the name of one of the Branches, beginning with the Rat in the north, and with special designations for the northeast, southeast, southwest, and northeast based on the names of the adjoining Branches. The northeast and southwest were considered unlucky directions (kimon and ura-kimon, respectively), forming the basis for the practice of avoiding traveling in those directions (katatagae).