The “Six Days” in the Japanese Calendar

This is one of those little reference posts I like to put up for people. If you look on a Japanese calendar you will often see a lot of extra characters like 大安, 仏滅, or 赤口, but what do these mean? For years, this drove me crazy. At my wife’s house in Japan they have one such calendar hanging in the bathroom, and whenever I had to go there, I would stare at the words trying to figure out what they meant, without any luck. The same words would just repeat every six days.

Finally, on my last trip, I picked up a helpful cultural guidebook, which explained them as the rokuyō (六曜) (also called rokki 六輝) which derive from the Chinese calendar of the 14th century, and Taoist folk beliefs at the time. The six days originally were used for gambling, but as they integrated into Japanese culture, they evolved and reflected auspicious and inauspicious day for things like weddings, the opening of a new Cabinet in the government, and other notable events.

According to the guidebook above, when the Meiji-era government sought to modernize and Westernize the country, they banned most superstitions, but allowed this one to remain in place because the Imperial family still conducted many events based on this ancient system. Thus it is one of the few such customs to survive into the modern era.

The six days, as you’ll see them on a typical calendar are in order:

Japanese Romaji/English Meaning
先勝 Senshō
“Victory first / before”
Mornings are lucky, but afternoons unlucky.
友引 Tomobiki
“Pulling friends”
Funerals on this day are thought to be dangerous on this day as the deceased might “pull” their friends into death with them. On the other hand, weddings occur on this day because friends are “pulled” into the good fortune. From 11am to 1pm, luck is especially bad.
先負 Senbu
“Loss first / before”
Mornings are unlucky, but afternoons are lucky.
仏滅 Butsumetsu
“Destruction of the Buddha”
The most inauspicious day. Wedding halls will have deep discounts because so few weddings are held on this day.
大安 Taian
“Great Peace”
The most auspicious of the six days. Weddings and store openings are held on this day, and even the Japanese National Cabinet is formed on this day when a new Cabinet is formed.
赤口 Shakkō
“Red Mouth”
The “red” here refers to fire and blood, and other inauspicious things. These days are only lucky from 11:00am to 1pm, and care should be given around knives and fire on these days.

The cycle works like so:

  • The 12 months in the year of the traditional calendar, or kyūreki (旧暦), do not line up with the Gregorian calendar.
  • Each “month” has 5 weeks, 6 days each, for a total of 30 days. Starting from the first day of the month, they go in the order above. However, even numbered months (2,4,6, etc) have an extra 31st day. Why? Who knows.
  • The first day of the month, however, also follows the cycle above. So the first day of the first month is Sensho, while the first day of the second month is Tomobiki and so on. The first day of the twelfth month is therefore Senbu (goes around twice).
  • Sometimes leap-months exist where a certain month is repeated twice. This is to correct the calendar when things get too far off, though I don’t know how this is actually calculated.

So, the first month might go day A, B, C, D, E, F, A, B, C and so on. But month 2 goes B, C, D, E, F, A, B, C, and month 3 goes C, D, E, F and so on. Calculating all this mathematically would be tricky.

The cyclical nature of the calendar, I think, speaks to the notion of cycles in Taoism and how good and bad fortune just come and go. Taoism at heart strives to teach people to just bend with the winds, as opposed to always trying to swim upstream, as people often try to do when ego and “self” are the most important thing in their lives. Some days are just going to be terrible, and some are just going to be good, with a lot of grey days in between.

Now, on the practical side of things, the six days are not observed much in Japan these days. As an experiment, I tried to follow these days on our calendar for a week or two to see if I could notice any difference in “luck” and I found no real difference from day to day. Sometimes, I had good luck on a “bad” day and bad luck on the “good” day. Also, I did the math, and was married on Shakkō in the later afternoon, a supposedly inauspicious time, and have been happily married for almost 6 years now, with a cute little addition to the family.1

However, the phenomenon itself, how it relates to the Imperial Family (which explains why it’s still even observed at all), and its origins are a point of interest for me. I think most people are not superstitious, but they may want to consult these days for that extra little boost of “luck” at important events. It may just be peace of mind, if nothing else, and I can definitely understand that. :) Of course, there are some superstitious people, just like every culture, but based on my experience, I believe the Six Days are more of a relic to most, or just something for the curious.

At any rate, it’s an interesting phenomenon and one of those things I’ve just wanted to post for a long time. Enjoy!

Update: Corrected incorrect information regarding how the cycle works.

1 Since folks have frequently asked, we’ve thought about a second one, but having just moved back into the US, and settled down, we just haven’t been able to focus on this yet. Holiday-related work is also taking up a lot of time as well.

8 thoughts on “The “Six Days” in the Japanese Calendar

  1. Amazing! I too have wondered about this. But here’s another twist to the story. My Japanese day planner only marks days that are 仏滅、大安 and 友引, while my Japanese wall calender dutifully marks all six. Does this mean that the three my day calendar lists are the most important to keep in mind when planning events?

  2. Hi Doug

    About this:

    “there are some exceptions to this pattern, for example, August 15th, is always butsumetsu, though I don’t have much information as to why.”

    Since the calendar has origins back to China it may be related to one of the two prominent days of year when the dead are honored. The first date is in the spring sometime and homage is paid to the ancestors (an infusion of Confucian tradition) and the second is this August date when the dead are believed to come out and visit the living (a combination of Popular Taoism and Folk Religion) The date is called 中元節 zhōngyuánjié

    Wikipedia has a fairly comprehensive description of the Ghost Festival here

    I had a chance to see some of the practices in Taiwan that go on during these festivals. There are a lot of spirit mediums who get a lot of work around that time as they “allow” the dead to become embodied.

    Burning of symbolic goods, spirit money and other offerings happen all over the cities and towns in the temples and sometimes just outdoors.

    On certain other special days throughout the year(calculated astrologically) there are related though less elaborate ceremonies and practices as well. I have seen some of these others being conducted by Buddhist priests. So there is quite a lot of cross-over between the Popular Taoism, Folk Religion and Popular Buddhist practices, in Taiwan anyways. I think this has hit a resurgence in Hong Kong as well as beginning to move back into mainland China.

    Very interesting post (as usual!)

  3. Hi guys:

    Adam: Very interesting that planner only highlights the most “significant” of the days. I guess the others are kind of mixed-luck and not worth calling out, whereas the ones listed are either really auspicious or really inauspicious.:)

    NellaLou: Wow, that’s a big help, thank you. This is interesting given that Japan doesn’t observe the Ghost Festival (though Obon is around the same time and vaguely analogous), so this must be a left-over from Chinese culture. Japan has a funny way of being a museum of Asian cultural bits lost elsewhere (e.g. use of Siddham sanskrit in liturgy, not used elsewhere). Thanks very much. :)

  4. Just a note- Rokuyo is based on the old Japanese calendar so in the modern day calendar, for example 15th of August this year is 赤口, 1st January is 大安. The old calendar would have the 26th of January as the first day of the year 先勝, and what was August 15th is now October 3rd this year 仏滅.

  5. Don’t know if this will be read, but I think the reason even months have an extra day is related to the moon cycles. For all I know, the japanese lunar calendar, which follows that pattern, was always corrected on days 1, 15 and 30, sometimes losing days inbetween, where 15 was always the full moon. Probably 31 is the perfect new moon, only happening on even months, where 1 and 30 are the just before and the just after.

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