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 ying aspects, the former designated by the Chinese character for "elder brother" and pronounced "e," the 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 names 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 rest may well cause trouble.

The following table lists the Ten Stems, showing how they are derived from the yang and ying aspects of the Five Elements. The relevant Chinese character can be read in either Japanese or Sinicized fashion; the latter is the reading used for enumerative purposes:

 

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 directions and hours of the day; they are also the versions that may be found today on Japanese New Year's cards. The following table lists the signs, their Japanese readings, and the standard Chinese characters that are used to represent the same animals today:

 

Finally, the Ten Stems and the Twelve Branches were matched sequentially in pairs (with the Five Elements always placed first) to give a total of 60 possible combinations, providing 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 passed through the entire cycle of 60 and reached the year with the same sign as the person's year of birth, it is referred to as that person's kanreki (that is, having reached the 61st calendar year of one's life, although now kanreki is often used to refer to one's 60th birthday). The possible permutations are as follows:

The Phases of the Moon (Getsurei) and Names of the Months

The traditional Japanese calendar was primarily a lunar calendar, and great attention was paid to the phases of the moon. A 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 the drawstring at the top (called jōgen no tsuki). As the moon waned, the bow arched upward and the moon became a kagen no tsuki, or "moon with the drawstring at the bottom" (in each case, the shape refers to 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:

 

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 of the year, along with two of the variants that were used and the names of the seasons associated with each month. For the problem of how synchronization with the solar year was handled, see the next tab.

The 24 Solar Terms - Nijūshi Sekki

Solar terms (sekki -- 節気）, which mark points 15 degrees apart along the solar elliptic, were used to adjust the differences that arose between the lunar calendar and the solar year. The winter solstice served as the starting point for these calculations. Each month had two points -- a setsu（節）and a chū（中）-- and each point was given a name that identified a particular season, with the chū point serving as the basis for giving the month its name. Intercalary months (urūziki -- 閏月) were inserted when the discrepancy between the lunar calendar and the solar year (as reckoned by sekki system) left a lunar month without a chū point, which happened about once every three years. The "empty" month (empty because the period between new moons did not contain a chū point, leaving the month without a name) was given the same name as the preceding month, preceded by the term jun（閏）. Thus jun-nigatsu would be the Intercalary Second Month of the year, following the usual First Month and Second Month. Lunar years normally contained about 354 days, while years with intercalary months were about 384 days long. It was an extraordinarily complex system.

The following table gives the names of the 24 solar terms, along with their approximate equivalents in the Gregorian system:

Directions and Times

In addition to their role as signs of the zodiac, the Twelve Branches were also used to refer to geographical directions and times of day. The following graphs illustrate the relationships.

Directions
Each of 12 directions took the name of one of the Branches, beginning with the Rat in the north, with the northeast, southeast, southwest, and northeast given special designations based on the names of the adjoining Branches. The northeast and southwest were considered unlucky directions (kimon and urakimon, respectively), forming the basis for the practice of avoiding them (katatagae).

 

Times
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, these two-hour periods were further divided into quarters. 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 there, with two times nine equal to 18, which, when the leading digit is ignored, 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.