Ever seen a Japanese calendar and wondered why each day is labeled with a word like 大安 or 仏滅? They don’t correspond to days of the week or anything else you’d find on a Western calendar. You might guess, then, that they have something to do with the lunar calendar. If so, you’d be right!
These words are part of a Japan-exclusive tradition called rokuyō. They will (purportedly) tell you which days are lucky and which days are unlucky, based on the lunar calendar.
Table of Contents
ToggleWhat Is Rokuyō?
The term rokuyō (六曜) refers to a repeating cycle of six days that predict the fortune of each day:
- Taian (大安): The luckiest day out of the six. Translated as “great peace,” Taian is a good day for weddings and other important events.
- Shakkō (赤口): A generally unlucky day. Only the period of time around noon, from 11 am to 1 pm, is auspicious on this day.
- Senshō (先勝): Morning is lucky, but afternoon is not. A good day to get things done quickly and early.
- Tomobiki (友引): On this day, morning and evening are lucky, with an unlucky period around noon that divides them. Because of its name, loosely translated as “pulling friends along,” Tomobiki is a bad day for funerals but a good day for weddings.
- Senbu (先負): The opposite of Senshō—morning is unlucky, while afternoon is lucky. One should avoid urgent matters and act calmly.
- Butsumetsu (仏滅): The unluckiest day among the rokuyō. This is essentially the polar opposite of Taian, so it’s a bad day for celebrations and other important happenings.
But how do you know which day of the year corresponds to which of the rokuyō? I’ll spare you the gory details, but the gist is that each day of the lunar calendar cycles through the six days of rokuyō in the order listed above. However, the first day of each lunar month is always a specific day. For instance, the first day of the first lunar month is always Senshō, while the first day of the second month is Tomobiki. One handy website[1] will give you any rokuyō day between 1900 and 2100.

History of Rokuyō
The exact origins of rokuyō are unknown, but it was introduced to Japan from China in the 14th century, toward the end of the Kamakura period. Although rokuyō apparently died out in its birth nation of China, it caught on in Japan.
Over the course of Japanese history, the practice of rokuyō evolved, partially due to the influence of a Japanese system of divination called onmyōdō (陰陽道). Among the things that changed were the names of the different days. For example, Butsumetsu used to be written with the characters 物滅 (literally, “[every]thing is destroyed”). This eventually evolved into the modern name 仏滅 (“Buddha is destroyed”) because of a mistaken popular belief that rokuyō originated from Buddhism.
The Meiji government denounced rokuyō as superstition in the late 19th century during a period of rapid Westernization. However, it would once again gain popularity among the people after World War II.
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Rokuyō in the Modern Day
According to tradition, one should consider the luckiness of a day when planning any major event, such as weddings, funerals, and celebrations. You’re even supposed to take rokuyō into account when deciding when to visit a friend or when to move. However, to what extent do Japanese people today subscribe to this tradition?
For starters, evidence shows that many Japanese companies pay attention to rokuyō. They often choose auspicious days, especially Taian, to start construction projects, launch products, move offices, and so forth. One example is Sony, which has launched (almost) all of its major products on Taian.
Gaijinhunter on X (formerly Twitter): “Fun fact: Japan uses a predetermined fortune telling calendar thing called Rokuyou (六曜) Six days. Most calendars have the type of day written on them by default. The most lucky day is Taian (大安). Every major PlayStation console launched on a 大安 day in Japan, except one. pic.twitter.com/sfzNHMJJsv / X”
Fun fact: Japan uses a predetermined fortune telling calendar thing called Rokuyou (六曜) Six days. Most calendars have the type of day written on them by default. The most lucky day is Taian (大安). Every major PlayStation console launched on a 大安 day in Japan, except one. pic.twitter.com/sfzNHMJJsv
When it comes to weddings, Japanese newlyweds today still prefer to get married on days that are considered auspicious under the rokuyō system, according to a survey by the wedding venue booking service Hanayume [2]. Over 40% of respondents chose days that corresponded to Taian (22.8%) and Tomobiki (18.0%). Meanwhile, less than 13% reported choosing the least auspicious days of Shakkō (5.1%) and Butsumetsu (7.5%). As a result, for prospective newlyweds, wedding venues tend to be more available on inauspicious days. Some venues will even slash prices for bookings on Butsumetsu.
Hanayume also asked in their survey whether newlyweds paid attention to the luckiness of a day when choosing their wedding day, to which 34.7% of respondents said that they did not.

More generally, an anonymous poll on the survey site Research Panel from 2015[3] indicated that 52.5% of respondents pay attention to rokuyō when planning events, compared to the 39.0% who said they didn’t. Some people admitted that they didn’t even know what rokuyō was (4.9%).
Below are some highlights from the comments in the poll. Interestingly, among the “No” voters, there were still folks who wrote that they do consider rokuyō to some degree.
Yes [Avoiding] Tomobiki for funerals and Butsumetsu for weddings… I have to say that I do keep [rokuyō] in mind.
Yes I pay attention to it for ceremonies more than events.
Yes I do because my parents care.
Yes I buy lottery tickets on Taian.
No Rokuyō has no basis in reality, so I don’t pay it any mind.
No I got lucky with a 50% off deal by holding my wedding on Butsumetsu. Needless to say, I’m still doing just fine.
No I don’t really know what it means, but I avoid Butsumetsu at least.
However, the large majority of Japanese people do not take rokuyō into account when moving to a new place. In a survey by logistics company Nippon Express[4], 80% of respondents said they do not consider rokuyō when moving. One such voter stated, “What matters more than rokuyō is a long weekend, so I can finish all the moving without having to take a day off.” In contrast, one of the other 20% said, “I’m superstitious when it comes to events. There are so many things to worry about when moving to a new place that any bit of reassurance is good.”
Finally, there is some data[5] showing that more hospital patients choose to be discharged on Taian than Butsumetsu. In other words, some patients will deliberately wait for a more auspicious day to be discharged.
Calendars and Superstition
All in all, the observance of rokuyō is much like any other cultural superstition. It varies not only from person to person but also from situation to situation. Among younger Japanese people especially, attention to rokuyō has been decreasing over time because of its association with older traditions. Today, a majority of Japanese people consider rokuyō for events like weddings but not for events like moving.
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But even among those who subscribe to rokuyō, only the two most extreme days, Taian and Butsumetsu, loom large in their minds. It is rare, for instance, to meet someone who plans their day around the lucky two-hour period on Shakkō.
Rokuyō is not the only calendar-related superstition in Japan either. There’s an older form of astrology called jūnichoku (十二直) that also originated in China. It defines twelve different types of days, each with its own degree of auspiciousness. And arguably the most popular out of all of these superstitions is the observation of unlucky years (厄年, yakudoshi), which could fill an entire article on its own!
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Sources
[1] 六曜 ROKUYO – Lucky and Unlucky Days. Seiyaku
[2] 仏滅の結婚式は縁起が悪い?仏滅に結婚式をしたカップルは7.5%!Hanayume
[3] イベントを行う時などに、六曜(大安・仏滅など)を気にしたことがありますか?Research Panel
[4] 引越しの時、「六曜」をあなたは気にする?Nittsu
[5] Exploring the causal relationship between length of stay in hospitals and treatment outcome: Evidence
from Japanese AMI patients. OSIPP