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）	甲	kō
Wood (yin)	ki-no-to （木の弟）	乙	otsu
Fire (yang)	hi-no-e （火の兄）	丙	hei
Fire (yin)	hi-no-to （火の弟）	丁	tei
Earth (yang)	tsuchi-no-e （土の兄）	茂	ho
Earth (yin)	tsuchi-no-to （土の弟）	己	ki
Metal (yang)	ka-no-e （金の兄）	庚	kō
Metal (yin)	ka-no-to （金の弟）	辛	shin
Water (yang)	mizu-no-e （水の兄）	壬	jin
Water (yin)	mizu-no-to （水の弟）	癸	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	子	ne	鼠
Ox	丑	ushi	牛
Tiger	寅	tora	虎
Rabbit	卯	u	兎
Dragon	辰	tatsu	龍
Snake	巳	mi	蛇
Horse	午	uma	馬
Sheep	未	hitsuji	羊
Monkey	申	saru	猿
Rooster	酉	tori	鶏
Dog	戌	inu	犬
Boar	亥	i	猪

 

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
61 kanreki （還暦）	甲子	ki-no-e ne [repeated]	kōshi / kasshi [repeated]

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 /  nemachi-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 / hatsuka-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 (sekki)	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).

Time

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.

Directions

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).