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 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:

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

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, 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 its drawstring at the top (the moon at this stage was called a jōgen no tsuki). As the moon waxed and then waned, the arch of the bow gradually moved upward and the moon took the shape of a kagen no tsuki, or "moon with the drawstring at the bottom" (in each case, the shape comes from 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, along with 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)
Fuzuki 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 chū (中) and a setsu (節) -- and each point was assigned a name associated with a particular season. The chū points provided the basis for numbering the sequence of the 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 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 a 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 contained 354 or 355 days, while years with intercalary months were either 383 or 384 days long. It was a cumbersome system, further complicated in 1844 by the adoption of an alternate method for measuring the distance traveled by the sun throughout different parts of the year (the latter system is what constitutes the kyūreki -- "old calendar" -- as it is understood today).

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 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

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 graphs illustrate the relationships.

* The diagrams may be freely reproduced in printed form, with an appropriate attribution. Online reproduction is prohibited.

The day was divided into halves, with the two-hour period centered on midnight designated as the Hour of the Rat. Midway points within the basic two-hour periods were designated as "halfway" points. When finer distinctions were necessary, the two-hour periods were divided into quarters (the designation ushi-mitsu, or "ox-three," for example, would thus refer to the 30-minute period 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 "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).



Diagram by Mark Jewel, Jlit website (