November Uncategorized

History and Origin of “Kotatsu” When Do We Get “Kotatsu” Out?



When it gets cold, we miss kotatsu, don’t we?  (A kotatsu is a traditional Japanese table with an electric heater attached to the underside.)

Many of you may have an experience of eating mandarin oranges in kotatsu and, there being so comfortable, lying down there for a while and falling asleep before realizing……

Not only human beings but also cats love kotatsu—as we sing in the lyrics of “Snow”, a famous Japanese nursery rhyme: “cats curl up in kotatsu”.  We should not get kotatsu out just because it has become cold; rather, there seems to be a day when we should get kotatsu out.

This time, I would like to talk about kotatsu, a heating appliance essential for cold seasons.



What are the History and Origin of Kotatsu?

The most prevalent etymology of kotatsu is said to be “kwatafshi”, a Tang (the dynasty which controlled China between 618-907) pronunciation of “火榻子” used by Zen (Buddhist) monks.

They associated the frame of kotatsu with shiji (“榻”), a step ladder used to descend from a cow carriage, and attached a suffix “子” at the end of “榻” (“子” is also used for equipment such as chairs (“椅子”)).




Kotatsu is said to have appeared in the Muromachi era (1336-1573).  At the time, they used a damped down irori (a traditional Japanese hearth sunken in the floor, which was used to heat home and cook food) with a stand covered with kimono (Japanese traditional clothes) over it.

During the Edo period (1603-1868), people started to use “yagura kotatsu” to keep warm, where they built a frame over irori and spread a kotatsu blanket on top of the frame.    Further along, in Meiji era (1868-1912), horigotatsu made its appearance.  This was an irori dug lower than the floor level, over which a frame was built at the same level as the floor.  A kotatsu blanket was spread over the frame, and people could tuck their legs in under the blanket.



The heat sources of kotatsu at the time were charcoal and tadon (ball-type dry fuel made by blending coal powder with binding agent).

However, they had a serious issue—there were risks of fire and carbon monoxide poisoning.  It is said that there were many occasions where young children died from accidents.




Electric kotatsu had already been launched in the late Taisho period.  It did not become popular, though.

After the war, desk-type kotatsus with a frame (okikotatsu) same as the modern kotatsu were launched.

They sold in huge numbers, since, unlike horigotatsu, people could put them anywhere and stretch their feet without cutting tatami (traditional straw mats) to make a hearth.  The ones with an infrared lamp which use radiant heat of infrared light became popular and the mainstream, as they became warm as soon as the switch was turned on and were also visually warm.



We Get Kotatsu Out on the Day of the Boar

The day when we should get kotatsu out is “the day of the ‘i’ (boar)” (the twelfth day of the 12-day cycle in Chinese zodiac order).

It is said that, during the Edo period, people called the day of the boar (as explained above) in the month of the boar (the twelfth month of the 12-month cycle in Chinese zodiac order) the "kotatsu biraki" (the opening day of kotatsu), and started to use kotatsu on this day of the year.

The samurai class is said to have taken out the heating appliances on “the first day of the boar in the month of the boar”, and the common people on “the second day of the boar in the month of the boar”.

“The month of the boar” is October of the old calendar (lunar calendar).  It is around November (of the current new calendar).

The day of the boar varies depending on the year; I will talk about it later.




“i” means boar.

Boars were said to be the shinshi (divine servants) of Marishiten (Marici, the guardian deity of the Buddhism and goddess of fire), and it was considered that they were safe from fire (they prevented fire).

Also, “i” is categorized into “water” in the Gogyo shiso theory (a concept of the natural philosophy where it is believed that everything is composed of the five elements of wood, fire, earth, metal, and water).  It is also categorized into “negatives” in the Onmyosetsu theory (the concept of classifying everything in the world into negatives and positives).  For these reasons, boars are considered to be able to control fire.



Based on the above, people prayed for fire protection of their home by starting to use heating appliances on the day of the boar.



When Shall We Take Out Kotatsu This Year (2020)?

The first day of the boar in the month of the boar in 2020 is November 4.

The second day of the boar in the month of the boar is November 11.

Unlike Edo period, we do not discriminate between the samurai class and common people. As such, there is no issue in getting kotatsu out on either of the two days of your choice.

If you would like to get kotatsu out earlier, or if you have forgotten to get kotatsu out on the abovementioned two days, you may as well consider getting it out on another “day of the boar”.

Beside the above mentioned two days, October 11, October 23, November 28, December 10 and December 22 are also “the days of the boar”.




It is interesting to know that kotatsu has been a heating appliance habitually used by Japanese since the Muromachi era.

Recently, new types of kotatsu have appeared that go with the times, such as a kotatsu for single use and a table for living room convertible to kotatsu (as we have limited living space).

The first day of the boar in the month of the boar appears to be around the beginning of November every year.  However, in the cold regions, people may get kotatsu out before then.

While being conscious of the dates for getting kotatsu out, we may as well take a flexible approach to lead a comfortable life.


-November, Uncategorized

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