The Japanese calendar

Period	Reign dates	No.	Names
-13000 to -300 JOMON -300 to 300 YAYOI	Legendary Emperors	1	Jimmu
		2	Suizei
		3	Annei
		4	Itoku
		5	Kôshô
		6	Kôan
		7	Kôrei
		8	Kôgen
		9	Kaika
		10	Sujin
		11	Suinin
		12	Seimu
		13	Keikô
		14	Chûai
300 to 710 YAMATO	Late 4th to early 5th century	15	Ôjin
	First half of the 5th century	16	Nintôku
		17	Richû
		18	Hanzei
	Mid-5th century	19	Ingyô
		20	Ankô
	Late 5th century	21	Yûryaku
		22	Seinei
		23	Kenzô
		24	Ninken
		25	Buretsu
	Early 6th century	26	Keitai
		27	Ankan
		28	Senka
	531 or 539-571	29	Kimmei
	572-585	30	Bidatsu
	585-587	31	Yômei
	587-592	32	Sushun
	593-628	33	Suiko
	629-641	34	Jomei
	642-645	35	Kôgyoku*
	645-654	36	Kôtoku
	655-661	37	Saimei*
	661-672	38	Tenji
	672	39	Kôbun
	672-686	40	Temmu
	686-697	41	Jitô*
	697-707	42	Mommu
	707-715	43	Gemmyô*
710 to 794 NARA	715-724	44	Genshô*
	724-749	45	Shômu
	749-758	46	Kôken*
	758-764	47	Junnin
	764-770	48	Shôtoku*
	770-781	49	Kônin
	781-806	50	Kammu
794 to 1185 HEIAN	806-809	51	Heizei
	809-823	52	Saga
	823-833	53	Junna
	833-850	54	Nimmyô
	850-858	55	Montoku
	858-876	56	Seiwa
	876-884	57	Yôzei
	884-887	58	Kôkô
	887-897	59	Uda
	897-930	60	Daigo
	930-946	61	Suzaku
	946-967	62	Murakami
	967-969	63	Reizei
	969-984	64	En'yû
	984-986	65	Kazan
	986-1011	66	Ichijô
	1011-1016	67	Sanjô
	1016-1036	68	Go-Ichijô
	1036-1045	69	Go-Suzaku
	1045-1068	70	Go-Reizei
	1068-1073	71	Go-Sanjô Shirakawa
	1073-1087	72	Shirakawa
	1087-1107	73	Horikawa
	1107-1123	74	Toba
	1123-1142	75	Sutoku
	1142-1155	76	Konoe
	1155-1158	77	Go-Shirakawa
	1158-1165	78	Nijô
	1165-1168	79	Rokujô
	1168-1180	80	Takakura
1185 to 1333 KAMAKURA	1180-1183	81	Antoku
	1183-1198	82	Go-Toba
	1198-1210	83	Tsuchimikado
	1210-1221	84	Juntoku
	1221	85	Chûkyô
	1221-1232	86	Go-Horikawa
	1232-1242	87	Shijô
	1242-1246	88	Go-Saga
	1246-1260	89	Go-Fukakusa
	1260-1274	90	Kameyama
	1274-1287	91	Go-Uda
	1287-1298	92	Fushimi
	1298-1301	93	Go-Fushimi
	1301-1308	94	Go-Nijô
	1308-1318	95	Hanazono
	1318-1339	96	Go-Daigo
1333 to 1573 MUROMACHI	1339-1368	97	Go-Murakami
	1368-1383	98	Chôkei
	1383-1392	99	Go-Kameyama
	1331-1333	1**	Kôgen
	1336-1348	2**	Kômyô
	1348-1351	3**	Sukô
	1351-1371	4**	Go-Kôgen
	1371-1382	5**	Go-En'yu
	1382-1412	100	Go-Komatsu
	1412-1428	101	Shôkô
	1428-1464	102	Go-Hanazono
	1464-1500	103	Go-Tsuchimikado
	1500-1526	104	Go-Kashiwabara
	1526-1557	105	Go-Nara
	1557-1586	106	Ôgimachi
1573 to 1603 AZUCHI-MOMOYAMA	1586-1611	107	Go-Yôzei
1603 to 1867 EDO	1611-1629	108	Go-Mizunoo
	1629-1643	109	Meishô*
	1643-1654	110	Go-Kômyô
	1655-1663	111	Gosai
	1663-1687	112	Reigen
	1687-1709	113	Higashiyama
	1709-1735	114	Nakamikado
	1735-1747	115	Sakuramachi
	1747-1762	116	Momozono
	1762-1771	117	Go-Sakuramchi*
	1771-1779	118	Go-Momozono
	1780-1817	119	Kôkaku
	1817-1846	120	Ninkô
	1846-1867	121	Kômei
1868 to 1911 MEIJI	1867-1912	122	Emperor Meiji (Mutsuhito during his lifetime)
1912 to 1925 TAISHO	1912-1926	123	Emperor Taisho (Yoshihito during his lifetime)
1926 to 1988 SHOWA	1926-1989	124	Emperor Showa (Hirohito during his lifetime)
1989 to ... HEISEI	1989	125	Akihito
* = empress
** = These five emperors are considered usurpers by the Japanese imperial house. Go-Komatsu, who inherited the throne usurped from Go-En'yu in 1382, was not officially recognized as emperor until 1392, when Go-Kameyama abdicated in his favor.

	Name			Date	Longitude
S1		Risshun	Beginning of spring	4 or 5 February	315
P1		Usui	Rains	18, 19 or 20 February	330
S2		Keichitsu	Awakening of insects	5 or 6 March	345
P2		Shunbun	Spring equinox	20 or 21 March	0
S3		Seimei	Clear light	4 or 5 April	15
P3		Koku-u	Hail rains	19, 20 or 21 April	30
S4		Rikka	Beginning of summer	6 or 7 May	45
P4		Shouman	Seed appearance	20, 21 or 22 May	60
S5		Boushu	Rising ears of grain	5, 6 or 7 June	75
P5		Geshi	Summer solstice	21 or 22 June	90
S6		Shousho	Lesser heat	6, 7 or 8 July	105
P6		Taisho	Greater heat	22, 23 or 24 July	120
S7		Risshu	Beginning of autumn	8 or 9 August	135
P7		Shosho	End of heat	22, 23 or 24 August	150
S8		Hakuro	White dew	7, 8 or 9 September	165
P8		Shuubun	Autumn equinox	22 or 23 September	180
S9		Kanro	Cold dew	8 or 9 October	195
P9		Soukou	White frost	23 or 24 October	210
S10		Rittou	Beginning of winter	7 or 8 November	225
P10		Shousetsu	Light snow	22 or 23 November	240
S11		Taisetsu	Heavy snow	6, 7 or 8 December	255
P11		Touji	Winter solstice	21, 22 or 23 December	270
S12		Shoukan	Lesser cold	5, 6 or 7 January	285
P12		Taikan	Greater cold	20 or 21 January	300

The lunar part of the Japanese calendar

Months

Unlike the Chinese, who had used true calculations to determine the lunar month since 1645, the Japanese adopted that method only in 1798.

As far as months are concerned, there are no major differences between the Chinese and Japanese calendars, except that before the Meiji period, months had agriculture-related names. This naming was later abandoned in favor of simple numbering.

Also note that month is called Zuki , the intercalary month is called Uruu , a "long" month is called Dai , and a "short" month is called Sho .

Days

The existence of a seven-day week is a distinctive feature of the Japanese calendar compared with the Chinese one. The names of these days are rooted in the solar system and appeared around 807.

Year names and the sexagesimal cycle

The sexagesimal cycle also exists in the Japanese calendar. The ten Heavenly Stems, called E (or Kan), and the twelve Earthly Branches, called TO (or Shi), are represented with Chinese characters. The operating principle is identical to the Chinese sexagesimal cycle.

Here is the Japanese E-to table:

* The first word corresponds to the so-called Chinese reading (“on-yomi”), more or less similar to the pronunciation of the character in China. The second corresponds to the so-called Japanese reading (“kun-yomi”), inherited from ancient Japanese before Chinese characters were introduced.

The year 2002 is also the Year of the Horse in Japan, according to the Chinese sexagesimal-cycle principle.

Japanese chronology

There are several systems for numbering years in Japan:

• The Nengo system
• The Kanshi system
• The Jimmu-tenno system

The Kanshi system is simply Chinese sexagesimal numbering. I must admit I do not know whether Japanese year 1 in this cycle is 2697 BC as in China. I assume so, since this is an “inherited” system, but I welcome any further information on this point.

In the Jimmu-tenno system, years are counted from the reign of the first emperor, Jimmu, in 660 BC. So year 2002 corresponds to Japanese year 2662.

The last system, Nengo, counts years from the start of a period (see chronology table at the top of the page) and restarts at 1 at each new period. Year 2002 corresponds to 14 Heisi. It is the most widely used system in Japan.

Here is the table showing the start of the different periods:

Japan adopted the Gregorian calendar in 1873, but the traditional calendar is still used for festival observances. Nengo year numbering and the sexagesimal cycle also remain alive.