1. Is Saturday a Weekday? Why Dictionary Definitions Differ
Basic definitions for "weekday" found on dictionary sites usually state: days other than Saturday, Sunday, and public holidays. Some of these sources add that Saturday is treated as a weekday or a holiday depending on the context [1].
The entry for "weekday" in the Digital Daijisen dictionary uses a more striking format: "Days other than Sunday, or days other than Saturday and Sunday." Here, the reading that counts Saturday as a weekday and the one that does not are listed together in a single explanation [2]. The definition "weekdays are Monday to Friday" does not apply in every situation. The day that causes confusion is always Saturday. The clue to this ambiguity lies in the history of how holidays were set.
2. Early Meiji Holidays: Government Offices Used Dates Ending in 1 and 6
About 150 years ago, holidays for government offices were not decided by days of the week. Instead, days with the numbers "1" and "6" in their date—such as the 1st, 6th, 11th, 16th, 21st, and 26th—were holidays [3]. This created a cycle of working for five days and resting for one, resulting in six days off per month.
On March 12, 1876 (Meiji 9), an order from the Dajokan (Grand Council of State) changed the rules. Sunday became a full holiday, and Saturday became a half-day holiday [3]. While the notice was issued in March, implementation of Sunday holidays is said to have begun in April.
When counting the days off, something interesting appears. Sundays occur four or five times a month. If you add Saturday half-days converted into full days, the total is between six and seven and a half days. This is not very different from the six days off under the "1 and 6" rule. The amount of rest remained similar; only the timing shifted from every five days to every seven days. Note that this calculation counts the rules in historical records, not actual working days at the time.
3. Saturday Half-Day Holidays (Handon) and the Two Ways Dictionaries Read "Weekday"
The term "handon" refers to the half-day holiday on Saturday. The origin of the word "don" is debated. One theory suggests it comes from the Dutch word for Sunday, zondag, which became "dontaku." Another theory says it comes from the sound "don" when blank cartridges were fired at noon. Neither explanation is confirmed [4].
If Saturday was a day where people worked half the time and rested half the time, it makes sense that dictionaries list two readings: "days other than Sunday" and "days other than Saturday and Sunday." However, this is an interpretation based on arranging historical events in order. Dictionary editors do not explicitly explain their choices this way.
4. Public Holidays and Government Office Rules: Weekdays That Are Days Off
In 1948 (Showa 23), the Law Concerning National Holidays was established. Article 3 states that "National Holidays" are holidays. If a holiday falls on a Sunday, the nearest following day that is not a national holiday becomes a substitute holiday [5].
For government offices, the Law Concerning Holidays of Administrative Organs (Law No. 91 of Showa 63) sets holidays as Saturdays, Sundays, National Holidays, and the period from December 29 to January 3 [6]. Even on weekdays within this year-end and New Year period, government offices generally do not work.
It is important to note that these are rules for government offices. They do not determine the scope of "weekday" for companies, shops, or trains. While the basic dictionary definition ("days other than Saturday, Sunday, and holidays") overlaps with this, government office holidays include the year-end/New Year break, making their scope wider.
5. When Saturday Became a Weekly Day Off in Schools
In current schools, Saturday is off, but it became a weekly holiday in April 2002. The change happened in stages: the second Saturday of each month became a holiday in September 1992, increased to twice a month in April 1995, and then became every Saturday [9].
For government employees and banks, full two-day weekends (Saturday and Sunday) are said to have started in 1989 according to encyclopedias [7]. However, other sources state that national public servants adopted this system in May 1992 [8]. Because the years do not match, it is safest to say this change happened from the late 1980s to the early 1990s.
In private companies, a 1999 survey showed that 91.3% of companies adopted some form of two-day weekend system, but only 14.5% had a full two-day weekend (both days off every week) [7]. The difference is about 77 percentage points. These figures represent the percentage of companies, not workers. They show that even if a company has a "two-day weekend system," it does not guarantee both Saturday and Sunday are off every week.
From 1876, when Sunday was established as a holiday, to 2002, when school Saturdays became weekly holidays, 126 years passed. Saturday can be counted as either a weekday or a holiday because it was a "half-working day" for a long time, slowly moving toward becoming a "resting day."
6. The Seven-Day Week and the Origins of Day Names
The seven-day cycle is explained in encyclopedias as having roots in Babylon, where the 7th, 14th, 21st, and 28th days were rest days. In Judaism, the seventh day is a day of rest. The seven-day cycle is thought to have been established in the Roman calendar around the 2nd or 1st century BC [11]. Originally, this was about cycles of rest.
In Japan, the seven luminaries (weekdays) are said to have been introduced through texts like the Sukiyo-kyo brought from Tang China by Kukai in 806. However, some encyclopedias date the introduction to around the 10th century, so there is a difference in records. Initially, these days were used as notes for fortune-telling calendars [10]. The oldest example of weekdays being written consecutively in a diary is said to be Fujiwara no Michinaga's Midokanpakuki (1004) [10].
The characters for the days correspond to celestial bodies: Sun, Moon, and the five visible planets (Mars, Mercury, Jupiter, Venus, Saturn). The "gold" in Friday refers to the planet Venus, not metal on Earth [12]. By 1876, when Sunday was set as a government holiday, more than 900 years had passed since the days were introduced.
7. Checking How Local Notices Use the Word "Weekday"
Look for notices at shops, libraries, or schools near your home that use the word "weekday." You may see phrases like "Weekdays (Mon-Fri)" or "Closed on Saturdays, Sundays, and holidays." The wording varies.
If you find these notices, check if Saturday is listed on the side of "weekday" or "holiday." If answers differ within the same town depending on the location, you have found an example of how the line for Saturday changes by context.