The Japanese calendar

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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 (gon; but pronounced "ka" in the system described below), 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 Sinicized readings 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 others 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 Twelve Branches (jūni-shi) comprise the signs of the traditional Chinese zodiac, which were given the names of animals (the Western zodiac, of course, also contains 12 signs). These signs were used to designate hours of the day and directions (see the other tabs for details). They are also the versions found today on Japanese New Year's cards. The following table lists the signs by their English name, the conventional Chinese character used to represent the sign, the Japanese reading for each character, and the standard Chinese character currently used to represent the same animal. Note that in Japan, "未" is usually treated as signifying "sheep" rather than "goat" or "ram," while "亥" is taken as signifying "boar" rather than "pig."

Sign Chinese character Japanese reading Standard character
Rat ne
Ox ushi
Tiger tora
Rabbit u
Dragon tatsu
Snake mi
Horse uma
Sheep hitsuji
Monkey  saru
Rooster    tori
Dog inu
Boar i


Finally, the Ten Stems and the Twelve Branches were matched sequentially in pairs -- always with one of the Five Elements first, beginning with wood, or ki -- to yield a total of 60 possible combinations. This method of sequential matching provided the system as a whole with its name: the Eto干支, or "Stem-Branch")System. This system is most commonly used today to identify the year of a person's birth, so that when an individual has completed the entire cycle of 60 and reached the year with the same sign as that person's year of birth, it is referred to as the person's kanreki (that is, having reached the 61st calendar year of one's life, although now kanreki is usually used simply to refer to one's 60th birthday). The possible permutations are as follows:

Year Compound Eto reading Sinicized reading
1 甲子 ki-no-e ne kōshi / kasshi
2 乙丑 ki-no-to ushi itchū
3 丙寅 hi-no-e tora heiin
4 丁卯 hi-no-to u teibō
5 戊辰 tsuchi-no-e tatsu boshin
6 己巳 tsuchi-no-to mi kishi
7 庚午 ka-no-e uma kōgo
8 辛未 ka-no-to hitsuji shinbi / shinmi
9 壬申 mizu-no-e saru jinshin
10 癸酉 mizu-no-to tori kiyū
11 甲戌 ki-no-e inu kōjutsu
12 乙亥 ki-no-to i itsugai
13 丙子 hi-no-e ne heishi
14 丁丑 hi-no-to ushi teichū
15 戊寅 tsuchi-no-e tora boin
16 己卯 tsuchi-no-to u kibō
17 庚辰 ka-no-e tatsu kōshi
18 辛巳 ka-no-to mi shinshi
19 壬午 mizu-no-e uma jingo
20 癸未 mizu-no-to hitsuji kibi / kimi
21 甲申 ki-no-e saru kōshin
22 乙酉 ki-no-to tori itsuyū
23 丙戌 hi-no-e inu heijutsu
24 丁亥 hi-no-to i teigai
25 戊子 tsuchi-no-e ne boshi
26 己丑 tsuchi-no-to ushi kichū
27 庚寅 ka-no-e tora kōin
28 辛卯 ka-no-to u shinbō
29 壬辰 mizu-no-e tatsu jinshin
30 癸巳 mizu-no-to mi kishi
31 甲午 ki-no-e uma kōgo
32 乙未 ki-no-to hitsuji itsubi / itsumi
33 丙申 hi-no-e saru heishin
34 丁酉 hi-no-to tori teiyū
35 戊戌 tsuchi-no-e inu bojutsu
36 己亥 tsuchi-no-to i kigai
37 庚子 ka-no-e ne kōshi
38 辛丑 ka-no-to ushi shinchū
39 壬寅 mizu-no-e tora jin'in
40 癸卯 mizu-no-to u kibō
41 甲辰 ki-no-e tatsu kōshin
42 乙巳 ki-no-to mi isshi
43 丙午 hi-no-e uma heigo
44 丁未 hi-no-to hitsuji teibi / teimi
45 戊申 tsuchi-no-e saru boshin
46 己酉 tsuchi-no-to tori kiyū
47 庚戌 ka-no-e inu kōjutsu
48 辛亥 ka-no-to i shingai
49 壬子 mizu-no-e ne jinshi
50 癸丑 mizu-no-to ushi kichū
51 甲寅 ki-no-e tora kōin
52 乙卯 ki-no-to u itsubō
53 丙辰 hi-no-e tatsu heishin
54 丁巳 hi-no-to mi teishi
55 戊午 tsuchi-no-e uma bogo
56 己未 tsuchi-no-to hitsuji kibi / kimi
57 庚申 ka-no-e saru kōshin
58 辛酉 ka-no-to tori shin'yū
59 壬戌 mizu-no-e inu jinjūtsu
60 癸亥 mizu-no-to i kigai

kanreki (還暦)

甲子 ki-no-e ne
kōshi / kasshi

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

The traditional Japanese calendar was a lunisolar calendar, and great attention was paid to the phases of the moon. A lunar month started and ended with the new moon (shingetsu), and a full moon (mochizuki or mangetsu) marked the middle of the month. Special terms were (and still are) used to describe the two half moons, the first appearing on day seven or eight of the month and the second on day 22 or 23: jōgen no tsuki (上弦の月, so called because the appearance of the setting moon was compared to a bow with its drawstring at the top) and kagen no tsuki (下弦の月, the appearance of the setting moon resembling a bow with its drawstring at the bottom).

The following table lists the other names that were used to describe the different phases of moon during the course of the month (hyphens added for clarity):

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, along with the corresponding season and two common name variants. For the problem of how synchronization with the solar year was handled, see the next tab.

Month Japanese Season Other names
Mutsuki 睦月 Spring 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)
Uzuki 卯月 Summer Natsuhazuki (夏初月), Hananokoshizuki (花残月)
Satsuki 皐月   Sakumozuki (さくも月), Tagusazuki (田草月)
Minazuki 水無月   Kazemachizuki (風待月), Seminohazuki (蝉葉月)
Fu(mi)zuki 文月 Autumn 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)
Kannazuki 神無月 Winter 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 signal seasonal events and also to reconcile the differences that arose between the lunar calendar and the solar year. The winter solstice served as the starting point for making these calculations (the winter solstice was by convention assigned to the Eleventh Month). Each month had two points -- a setsu (節) and a chū (中) -- and each point was assigned a name associated with a particular season. The chū points provided the basis for numbering the sequence of the lunar (calendrical) months, thus establishing the connection between the two systems.

Intercalary months (urūzuki -- 閏月) were inserted when the discrepancy between the solar year (the distance between two chū points being about 30.4 days) and the nominally 30-day lunar calendar (in which the moon completes its cycle in about 29.5 days) left a month without a solar chū point, which in classical times happened about once every three years. The extra "empty" month (that is, lacking the chū point necessary for establishing a position in the overall sequence) was given the same number as the previous month, preceded by the term jun (閏). Thus, jun-nigatsu would be the Intercalary Second Month of the year, following the usual Second Month. The addition of the extra month would bring the two systems back into alignment. Years with the standard 12 lunar months -- which themselves could be either 29 or 30 days long -- actually contained 354 or 355 days, while years with intercalary months were either 383 or 384 days long. It was a cumbersome system that reached its final iteration in 1844, when the calendar -- referred to since the Meiji period as the kyūreki, or "old calendar" -- was officially revised in accordance with Japanese methodology for the fourth time in history (the first revision had come in 1685).

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

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

Time and directions

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 diagrams illustrate the relationships (the diagrams may be freely reproduced in printed form -- with an appropriate attribution -- but online use is prohibited).


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, the two-hour periods were divided into numbered quarters of 30 minutes each; the designation ushi-mitsu, or "ox-three," for example, would refer to the 30-minute period between 2:00 am and 2:30 am, the third quarter of the Hour of the Ox.

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"). The points midway to the next "hour" were designated "halfway" points (-han; ~半).

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 diagram cannot be considered perfectly reliable in all cases.

Time of Day

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

Classical Directions