Calendar and Time

by Anthony J. Bryant

Era names

Unlike the Christian West, which uses computation based on the birth of Jesus Christ from which to date events, or the Ancient Romans who used the founding of the city as their pivotal date, or the Muslims who date everything from the Hegira, the Japanese have no single date to use. Actually, they could have used the mythical foundation of the empire in 660 BC, but in Period they never did so formally. From the seventh century down to the present, Japan has used a series of era names called nengō (= year number), assigning events to a year within that era. From time to time, usually due to some great auspicious event or to end a bad era after a particular bad calamity, an emperor proclaims a new nengō. Some nengō span several reigns; some reigns saw many nengō come and go.

The system has a flaw. The longer one's history gets, the harder it is to put things into historical context without having recourse to a list of era names and their volume of years. Even historically, people found it difficult to keep track of era names and when things happened. Was Emperor Horikawa enthroned in Kanji 1 or in Ōtoku 3? And if this year is the year of the Battle of Sekigahara (Keichō 5), how many years ago was that? (Ōtoku 3, and it was 514 years ago.)

In the 955 years between the institution of the nengō system in 645 and the Battle of Sekigahara in 1600, there were 194 nengō, for an average of one every 4.92 years.

The sexagesimal system

The Japanese adopted the complex sexagesimal system of year identification from the Chinese in 604. In this calendar system, there are 10 “trunks” and 12 “branches” that combine to form 60 terms for counting the years. These 60 years cycle over and over, so that since 1500 was Mizu-no-to U (= “[the Year of the] Hare, Younger Brother of Water”), then 1561 and 1622 were also.

Although it may at first seem cumbersome, it would be good to remember the basics of this system, for with it one can also identify hours of the day, days of the week, and so on. First we must look at the “ten trunks.” These trunks represent aspects of the five elements, namely wood, fire, earth, metal, and water. Five of the ten trunks represent the “elder brother” (e) of the five elements while the remaining five represent the “younger brother” (to) of the elements.

The ten trunks are: for wood, Ki-no-e and Ki-no-to (Elder Brother of Wood and Younger Brother of Wood); for fire, Hi-no-e and Hi-no-to (Elder Brother of Fire and Younger Brother of Fire); for earth, Tsuchi-no-e and Tsuchi-no-to (Elder Brother of Earth, Younger Brother of Earth); for metal, Ka-no-e and Ka-no-to (Elder Brother of Metal and Younger Brother of Metal); and for water, Mizu-no-e and Mizu-no-to (Elder Brother of Water and Younger Brother of Water). The chart above-left shows their relationships. These ten elements can be written one of two ways: with the full kanji that literally spell out the phrase, or with a single “shorthand” kanji that has the same reading as the full phrase. In the chart above, the kanji in the parentheses are the “shorthand” versions typically used.

The twelve branches are the twelve animals of the Chinese zodiac, namely: ne (rat), ushi (ox), tora (tiger), u (hare), tatsu (dragon), mi (snake), uma (horse), hitsuji (goat), saru (monkey), tori (cock), inu (dog), and i (boar). The chart at right above shows the twelve branches. For astrological and calendrical function, the names of these animals are written with different characters than are used to conventionally write their names. Here, the kanji in parentheses is the “typical” one used to write the word, while the kanji at the head of the list is the astronomical one.

These two units combine to form compounds such as Kanoe inu ("Year of the Dog, Elder brother of metal"). Japan and China still use a simplified form of this system, where the zodiac animals rotate through in 12-year cycles and the additional element of the trunks is eliminated.

Below is the full cycle of sixty combinations with the ten trunks and twelve branches. Number sixty-one is identical to number one, i.e., “Kinoe ne — Elder brother of wood, rat.”

For those who are curious, the year 2004 is Kinoe saru, “Year of the monkey, elder brother of wood” (number 21 on the chart). The year 1600, the year the Battle of Sekigahara was fought, was Kanoe ne, “Year of the rat, elder brother of metal” (number 37 on the chart).

Click here for a chart detailing the entire period from 645 to 2008, year by year, listing the era name and the sexagesimal names in English.

Months, weeks, and days

In Europe, the equinoxes and solstices mark the beginning of the four seasons; in China and Japan, however, they fall dead in the center of seasons.

Generally speaking, the Japanese calendar follows the lunar cycle. The first lunar month of the year is when the Sun enters the sign of the fish (sometime between January 20 and February 19, typically around February 5). One year consists of 12 months, so each year had 360 days.

The months are either just numbered (e.g., First Month, Second Month, etc.) or are called by one of several colorful variants.

On years in which the sun still hasn’t entered the Fish by February 19, a thirteenth, intercalary month is added, bringing the year to 390 days in number.

If there is an extra month in any year, it is called by the name of the month in which the Sun remains in the same sign, with the prefix Uru~, so if the month stays in Kaminazuki too long, there is an Uru-Kaminazuki.

It was not a very efficient system.

Each month had 30 days, and was nominally made up of three ten-day weeks. The last day in each week is taken to be a general day of rest. The first day of each month is called Tsuitachi, and the last day — a bigger deal of a “day off” than the tenth and twentieth — is called Misoka. The last day of the year is called Ō-Misoka (= Great Misoka).

Japanese do not seem to have had names for their individual days in quite the same way we in the West think of names for days of the week. Someone would not say “We attack on Wednesday” — rather, they seem to have used the date (e.g., “We attack on the fifteenth”) or perhaps even the phase of the moon. More than one source suggests that they may have used the Chinese reading of the names of the ten trunks (rather than using them as references to their position as elder or younger brothers of the five elements), namely Kō, Otsu, Hei, Tei, Bo, Ki, Kō, Shin, Jin, and Ki, although this is not certain.

The sexagesimal cycle itself has also been used for the days, beginning at the first day of the year, so that every two months the cycle repeats. In this instance, the first day of the year is Kinoe ne, or "Day of the Rat, Older Brother of Wood."

Telling time

There are actually several ways of telling time in Japan. (Did you think that it could be easy?)

The principal method of telling time is actually rather easy. The day is divided into twelve rôkoku or koku (“hours” for want of a better term, although one koku is equal to two modern hours) and is given the name of one of the animals from the zodiac. For example, the Hour of the Horse, or Uma no koku, corresponds to 11 a.m. – 1 p.m. on a modern clock. Today, it is unclear when a text says “exactly at the hour of the ox” (for example) it means at the beginning of that time or spot on the middle of it.

The second method assigns numbers to the hours according to order, decreasing from nine to four (i.e., Ninth Hour at noon and midnight, Eighth Hour, from one to two, Seventh Hour from three to four, etc.). There doesn't seem to be any rhyme or reason for the assignment of these numbers, but throughout the towns or cities, in temples and castles, drums or bells would sound the number corresponding to the number assigned (not unlike "four bells" aboard ship).

The graphics here shows the corresponding hours of the Japanese day with the hours on a Western twenty-four-hour clock. The pale yellow ring is the zodiac method of identifying the hours; the blue ring is the bells method; the yellow arch shows the five standard watches of night-time, beginning at seven p.m. (the hour of the Dog).

Where things can get complicated is in the area of allocating time for the hours on the clock. One method, with “set” times, is designed so that there is an even number of hours of daylight and of night time, regardless of how long or short each ended up being. This results in a clock that indicates an equal number of very long daytime hours and very short nighttime hours in the summer and visa-versa during the winter. The more complicated system would take into account the actual length of the night and the day in different seasons, so at some parts of the year the night-time hours would be shorter, and at other seasons longer. The graphic below displays this variation. The top bar represents summer, the bottom winter; the middle is spring and fall.