六曜 ROKUYO – Lucky and Unlucky Days in Japan

The history of the Japanese calendar is fascinating. Since 800 AD, Japan has used a seven day week, with names for the days corresponding directly to those used in Europe. This system was used for astrological purposes and little else until 1876, shortly after Japan officially adopted the Western calendar. After that date, they became the official names for the days of the week.

The seven day names were simply from the Chinese philosophies of yin-yang, plus the five classical Taoist elements: fire, water, wood, metal, and earth.

Sunday - nichi-youbi (yang - sun) Monday - getsu-youbi (yin - moon) Tuesday - ka-youbi (fire) Wednesday - sui-youbi (water) Thursday - moku-youbi (wood) Friday - kin-youbi (metal/gold) Saturday - dou-youbi (earth)

Yang and Yin 5 elements

Although the seven days have been used in Japan for around 1,200 years, until the 19th century they also had a parallel six-day system, which had more effect on daily life than the seven-day astrological system. (Hey! Let's go back to that system; abolish Mondays!) The six days were known as Rokuyo (roku - six, yo - day) and were based on superstition of good and bad luck. Rokuyo no longer forms part of the official calendar in Japan, but it can still often be seen in small print.

Each Rokuyo day has a name and an associated meaning:

The days basically follow the cycle from Sakigachi to Shakku, as listed in the above table. There are exceptions; the first days of months in the old Chinese lunar calendar are always assigned the same Rokuyo day:

If you want to calculate Rokuyo days for yourself, the easiest way is to learn Japanese and study one of the many Japanese web pages that explain it.

But if you don't want to spend years learning Japanese then here's an important point to remember: Rokuyo was invented to give people like you and me a headache. The complicated calculation alone is evidence that somebody, years ago, thought: "Let's have some fun and plant a mental time bomb for foreigners, hundreds of years from now."

Success!

The six-day cycle is not regular; as you see in the table above the cycle is reset at the start of each lunar month. Why? Who knows, but that's what it does. And if you remember from junior school, the average length of a synodic month is 29.530589 days. That means two things: (1) Some months are 29 days, some are 30, and we throw in an extra day from time to time to smooth things out. (2) They teach us some awesome stuff at school which we thought we'd never need. How wrong we were.

The first day of a month is the day when an astronomical new moon occurs in a particular time zone, and that introduces yet another problem (as they say in Japanese Naki-ttsura ni hachi¹). Should we calculate using Japanese time or GMT? Or since the calendar originated in China, precisely which longitude applies?

Having decided that, we next superimpose the result over our current Western calendar, which has a different number of days each month (28, 29, 30 or 31) and the end result is the search for the aspirin. Hopefully we also realise that if we delve into the 'time' thing too deeply then we can drift into the esoteric nature of time, start chanting weird things and get taken away by men in white coats.

Fortunately there's no need for you to calculate this for yourself at all. We publish the Rokuyo for every day from 2000 to 2050 here.

In January 1873, despite incredible turmoil going on at the time, Japan changed from the lunar system to the solar (Gregorian) calendar system as part of their plan to trade more easily with the West.

In addition to adopting the western calendar, they changed the length of the 'hours'. This was an incredibly brave move and something that few would seriously contemplate today (except perhaps for proponents of the Metric or Decimalized Time system).

Before 1873, Japan used an interesting time system based on a 'day', starting at dawn, and a 'night', starting at sunset. The 'day' was sub-divided into six equal-length 'hours', and the 'night' was sub-divided into six equal-length 'hours'. As the seasons stretched the days or nights, the length of these 'hours' was constantly changing. Accurately altering the regulator on early clocks every couple of weeks was a nightmare and was quite a challenge for the early clockmakers. (Did people really use their pulse for finer time-measurement? ²) All that changed in 1873, and a few years later, young Kintaro Hattori established K Hattori &Co., Ltd., the predecessor of what became the Seiko Corporation.

These exciting developments made little difference to most people however; farming continued to be governed by the unofficial yet ancient solar calendar developed by Chinese astronomers, the seasons and the weather. And of course trains on the newly opened Tokyo to Yokohama rail link ran on time.

For its international commercial image however, changes made by people such as Hattori brought Japan right up to date with the rest of the world.

But the superstitions based on 'time' remained. Few Japanese would admit to serious belief of the system now, but a Pascalian 'better be safe than sorry' attitude is common when arranging things. (See also superstitions)

When attempting to make a baby, Rokuyo is not known to be an effective 'marital aid'.

The evidence of any Rokuyo effect on birth delivery days is very thin and unlikely to feature much in the parents' decision making. Only a fool would risk messing about with nature by relying on superstition; it goes against natural human behaviour to put one's offspring at risk.

To trust an ancient custom with a dodgy reputation (see why we don't believe in Rokuyo) would be to say that Rokuyo had miraculous powers, and it is commonly accepted that miracles are the working of a divine power. If you feel that Rokuyo or astrology is divine, then you are missing out on something infinitely more wonderful.

Until recently, deciding on which day a baby is born has not been possible. But more recently, with the advent of induced labour, there is a slight tendency for some parents to request delaying birth by a day or two, or hastening it, to avoid Butsumetsu or to coincide with Taian. Doctors, naturally, discourage such approaches.

This happens not only in Japan but all across Asia. In Taiwan, for example, a study in 2003 showed increases in scheduled births on auspicious days and decreases on inauspicious days, according to the Chinese lunar calendar.³ However, in the vast majority of cases the joy of having a baby, plus the enormous demands that can cause such a strain, don't leave much time for parents to consider Rokuyo very much, if at all.

Rather than the parents deciding the delivery date, their doctor, who is ever mindful of the necessity to have happy parents rear a child, will always advise that the best day is the day decided by the baby. With the advances in medicine, it may be possible in the future to have such designer births with no risk to the child. Whether this will happen before the Rokuyo system fades from Japanese culture remains to be seen.

Having said all that, conscious decision making may be a waste of time. In 2011, researchers at Yale School of Public Health examined 1.8 million U.S. birth certificates over an 11-year period and found that birth rates dropped by 11% on spooky Halloween, when compared with one week on either side of the date. This applied to both 'natural' and induced births. They also noted a 3.6% increase in spontaneous births and a 12.1% increase in cesarean births on Valentine's Day. The study suggested that a psychological influence over hormonal activity may be at work.⁴

Traditionally Taian is the most popular day to tie the knot and Butsumetsu is the least favourite. However, in the current uncertain economy, money has become a significant factor in deciding the best day for a wedding.

Due to the passing of the baby boom of 25-30 years ago, fewer people will reach the marrying age in the foreseeable future. Therefore wedding companies face the double problem of a shrinking market and an economy that has been weak since the 90s. In response, many companies today are offering a special discount to people who use their services on a Butsumetsu day. This incentive has had the effect that the peaks and troughs seen in a typical wedding week a few years ago are now levelling off. The cost of offering the incentive is more than made up by the efficiency gained in the more balanced use of resources throughout the week.

Those who choose to marry on a Butsumetsu that is also Friday the 13th, are more likely interested in saving money, rather than being superstitious.

(See also Lucky Horseshoe and Western-style Weddings in Japan)

Rokuyo has no part to play in the timing of death. In special cases, death can be scheduled; for example when the life-support equipment or medication is withdrawn from a terminally ill patient, or for prisoner execution, murder or suicide. There is clearly no place for superstition in any of such scheduling.⁵

For funerals, a ceremony on Butsumetsu may give the bereaved a little extra comfort.

Tomobiki is supposed to be bad, bad news, because the word translates as 'pulling a friend'. It conjures the image of being pulled into death to go with your friend. If a funeral really must take place on that day, folklore tells of a doll placed in the coffin so that it, and not a friend, is dragged to the next life.

(And if you think that is not 100% codswallop, then we invite you to suggest how some supernatural entity can be powerful enough to pull somebody into death, but unable to differentiate between a doll and a human.⁶)

As with birth delivery days, the use of Rokuyo does not feature much in medical treatment because such events tend to be too important to risk relying on superstition. To trust an ancient custom with a dodgy reputation (see why we don't believe in Rokuyo) would be to say that Rokuyo had miraculous powers, and it is commonly accepted that miracles are the working of a divine power. If you feel that Rokuyo or astrology is divine, then you are missing out on something infinitely more wonderful.

Mankind has an inherent and healthy fear of sickness. No sane superstitious person⁷ would consider agreeing to surgery on Butsumetsu.

Some people may also consider Rokuyo when being discharged from a hospital⁸. The unlucky day Butsumetsu often precedes the lucky day Taian. Rather than risk discharge on an unlucky day, there is evidence that some patients extend their stay by an extra 24 hours to be discharged on Taian. This may sound quaint, but a consequence is an increased cost of medical care in Japan. A relatively small increase of course, but given the billions of yen cost of medical care, this extra astrologically inspired cost has astronomical proportions.

A similar phenomenon affects Western hospitals, with patients avoiding surgery on Friday the 13th.

Should the days of Rokuyo concern the Western businessman negotiating with Japanese? Well, there is plenty of evidence that Japanese businessmen do consider superstitions when they are making choices.

Look, for example, at the popular story of the largest Japanese car maker. The company started with the owner's name, Toyoda, but gave the launch an extra bit of luck by naming the company Toyota. And that is luckier because to spell Toyota using katakana, you use eight pen strokes. (トヨタ) and eight is a lucky number. Silly? Maybe. But Toyota has been pretty successful over the years.

Do Japanese businessmen consider superstitious days? Can we examine how they behave and use this information to model our own behaviour and improve our chances?

Here are a few clues. For some Japanese companies:

• commercial and domestic construction projects often start on Taian
• new or refurbished branch offices delay opening until the next Taian
• office moves are scheduled for Taian
• product launches avoid Butsumetsu
• electric power companies report to the Ministry of Economy and Industry every time they change their charging rates, always on Taian.

However these examples are about as far as it goes.

If you are about to do business with a Japanese company, don't fret about lunar calendars at the expense of improving the quality of the product or service you are trying to sell. Our overall recommendation is to not worry about Rokuyo. As with the popular discounts offered to couples to marry on Butsumetsu, business is about money, and the opportunity for profit tends to be a much more powerful influence than superstition.

And a note about national holidays in Japan: Despite the apparently large number of Japanese tourists, many Japanese workers traditionally don't take all their annual leave entitlement. So when the office closes for a National Holiday in Japan, those days are especially precious. Arrange a teleconference call on one of those days and see how quickly you lose favour with your Japanese customers.

The end of the baby boom could itself be the result of a superstition. Hinoe-Uma is a calendar event that occurs every 60 years.

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