What Are Japan’s 72 Micro-Seasons? | The Calendar That Renames the Year Every Five Days, Explained Gently for Beginners

Today, the Japanese calendar moved one notch forward.

August 23rd. From today begins a season called Shosho — written with a character meaning “to settle, to come to rest,” and understood as the time when the heat finally begins to subside.

But the Japanese calendar has a finer set of markings than that. It divides the year into seventy-two.

On that scale, the five days beginning today carry a name of their own:

Wata no hana-shibe hiraku (綿柎開)
— when the husk around the cotton boll begins to open

A name made for five days and nothing more. Here is that calendar — the shichijuni-ko, the seventy-two micro-seasons — traced gently for those meeting it for the first time.

What are the seventy-two micro-seasons?

The shichijuni-ko divide the year into seventy-two named stretches of about five days each.

To see where they come from, it helps to know the coarser scale first.

The nijushi-sekki, the twenty-four solar terms, divide the year into twenty-four. Risshun (start of spring), Geshi (summer solstice), Risshu (start of autumn), Toji (winter solstice). When a Japanese news broadcast says “on the calendar, autumn begins today,” this is what it is referring to. Each term runs about fifteen days.

The seventy-two micro-seasons are simply each solar term cut into three.

Twenty-four solar terms — the year ÷ 24 ≈ 15 days each
Seventy-two micro-seasons — each term ÷ 3 ≈ 5 days each (24 × 3 = 72)

The three are called, in order, shoko (first), jiko (second) and makko (last).

Five days is a startlingly short unit for a season. The four seasons give you three months each; the solar terms, a fortnight. The micro-seasons are shorter than a week. That is how finely this calendar set out to cut the year.

The word “climate” still carries it

Here is a small pleasure of learning this.

Japanese and Chinese share a word for climate: kiko (気候). An entirely ordinary word, the kind you find in a weather report.

It is said to be made of two borrowed pieces: the ki (気) of the twenty-four solar terms, and the ko (候) of the seventy-two micro-seasons.

Which would mean that “climate,” in East Asia, began life as the names of two calendar units stuck together — an old almanac sitting fossilised inside a word nobody thinks twice about.

(This etymology is widely repeated in calendar writing; we pass it on here as such rather than as settled fact.)

The names read like very short poems

The best thing about the seventy-two micro-seasons is, quite simply, the seventy-two names.

Each is three or four characters long, and each states in one breath what is happening outside. A handful of them:

Harukaze kori wo toku (東風解凍) — the spring wind begins to melt the ice [Risshun, first]
Sugomori mushi to wo hiraku (蟄虫啓戸) — insects that wintered underground open their doors [Keichitsu, first]
Sakura hajimete hiraku (桜始開) — the cherry trees begin to open [Shunbun, second]
Tsubame kitaru (玄鳥至) — the swallows arrive [Seimei, first]
Kaiko okite kuwa wo hamu (蚕起食桑) — the silkworms wake and eat mulberry [Shoman, first]
Suzukaze itaru (涼風至) — a cool wind arrives [Risshu, first]
Kusa no tsuyu shiroshi (草露白) — the dew on the grass looks white [Hakuro, first]
Kirigirisu to ni ari (蟋蟀在戸) — the crickets are at the doorway [Kanro, last]
Sora samuku fuyu to naru (閉塞成冬) — the sky closes over, and it becomes winter [Taisetsu, first]
Natsukarekusa shozu (乃東生) — the grass that withers in summer puts out its shoots [Toji, first]

Something stands out. None of them has a human subject.

Wind, insects, cherry trees, swallows, silkworms, dew, sky, grass. Every subject is something other than us. A calendar is normally a list of human appointments; this one reads like a schedule kept by everything else.

And the names never argue. “Insects open their doors.” “The sky closes over, and it becomes winter.” An observation set down and left there.

Less explanation than sketch. Which is why reading through the list of seventy-two feels less like consulting an almanac than leafing through a book of poems.

Born in China, rewritten in Japan

The seventy-two micro-seasons were devised in ancient China, and came to Japan alongside the twenty-four solar terms.

Which created a problem. China and Japan do not share a climate, or a cast of creatures.

Used unaltered, the Chinese names would have had the calendar announce events that simply do not happen in Japan. So Japanese calendar scholars rewrote them to fit the country they were standing in.

Central to that work was Shibukawa Harumi (also read Shunkai, 1639–1715). Rather than importing Chinese calendrical method wholesale, he accounted for things like the difference in longitude between China and Japan, and produced the Jokyo calendar, in use from 1685 — remembered as the first calendar reform carried out by a Japanese astronomer. He went on to become the shogunate’s first tenmonkata, the official charged with the calendar and the heavens.

Shibukawa and his fellow scholars revised the seventy-two micro-seasons for Japan as well. The result is known as the Honcho shichijuni-ko — honcho meaning “this country of ours.”

How much changed? Compare the three micro-seasons of the spring equinox:

	China (Senmyo calendar)	Japan (Ryakuhonreki)
First	玄鳥至 — the swallows arrive	雀始巣 — the sparrows begin to nest
Second	雷乃発声 — thunder begins to sound	桜始開 — the cherry trees begin to open
Last	始電 — lightning begins to show	雷乃発声 — thunder begins to sound

The cherry blossom was written into the equinox. That line does not exist in the Chinese calendar. Ask what actually happens in Japan in late March and the answer is: long before the thunder, the cherry trees open. So in went the cherry trees.

A calendar was imported, and then looked at again with local eyes. In the seventy-two micro-seasons, the marks left by that second look are easier to see than anywhere else.

The version mainly used in Japan today is the one printed in the Ryakuhonreki of 1874, the abbreviated almanac of the Meiji era. The names were adjusted more than once on the way from Edo to modern Japan.

Where we are right now

In 2026, Shosho runs from August 23rd to September 6th. Those fifteen days split into three.

	Name	Meaning	2026
First	綿柎開 wata no hana-shibe hiraku	the husk around the cotton boll begins to open	from around Aug 23
Second	天地始粛 tenchi hajimete samushi	the heat of heaven and earth at last begins to settle	from around Aug 28
Last	禾乃登 kokumono sunawachi minoru	the rice ripens and the ears bow down	from around Sep 2

Laid out that way, the fifteen days turn into a small story: the cotton opens → the heat settles → the rice ripens.

Honestly, late August in Japan is still extremely hot. “The heat of heaven and earth at last begins to settle” is not what the air feels like; the calendar and the thermometer are some distance apart.

And yet, having the name placed there first, you find yourself looking for the sign. The evening wind is slightly different. The light goes earlier. The cicadas have changed shift. The name is what makes the change noticeable. That order of events is real.

A loose way to use it

The seventy-two micro-seasons are not something to memorise. Nobody needs seventy-two names. There is really only one way worth recommending:

Know the name of the one you are in.

That is enough for the season to change its name every five days. Not counting down like a calendar, just noticing: apparently this is the sort of season it is right now.

In Japan the system surfaces in odd corners of daily life — the menu at a wagashi shop, the scroll hanging in a tearoom, the season-words of haiku, a passing line in a weather forecast. Knowing about it turns those into something you recognise rather than something you skim past.

If you are travelling here, better still. Find out what the calendar is saying on that day, in that place. It can outlast the names of the sights in your memory.

To close

Cutting the year into seventy-two is, on reflection, an extravagant thing to do. Naming every five days and writing it into the almanac is less a practical measure than a form of insistence.

But what the fineness was for, most likely, was not missing anything.

Seasons change slowly. Slowly enough that by the time you notice, the change is over. No date is fixed for the end of summer; nothing sounds to mark the start of autumn. So people set out small headings every five days — so that the calendar itself could say, this is around the time the cotton opens.

Today, Japan entered wata no hana-shibe hiraku: the husk around the cotton boll begins to open, and something white starts to show.

There need not be a cotton field anywhere near you. If, over the next five days, the sky or the wind looks a little different than it did — that is already a perfectly correct use of the seventy-two micro-seasons.

Sources

Wikipedia (Japanese), “七十二候” — https://ja.wikipedia.org/wiki/七十二候
Wikipedia (Japanese), “渋川春海” — https://ja.wikipedia.org/wiki/渋川春海
National Astronomical Observatory of Japan, Koyomi Wiki, “Shibukawa Harumi and the Jokyo calendar” — https://eco.mtk.nao.ac.jp/koyomi/wiki/CEF2BBCB2FC6FCCBDCA4CECEF12F2.BDC2C0EEBDD5B3A4A4C8C4E7B5FDCEF1.html
National Astronomical Observatory of Japan, Almanac for Reiwa 8 (2026), Twenty-Four Solar Terms — https://eco.mtk.nao.ac.jp/koyomi/yoko/2026/rekiyou262.html
All About, “What is Shosho? When is it in 2026? Meaning, customs and micro-seasons” — https://allabout.co.jp/gm/gc/488818/
Japanese Culture Research Blog, “The seventy-two micro-seasons: readings and meanings” — https://jpnculture.net/shichijunikou/
Aina Satoyama Park (Akashi Kaikyo National Government Park), “Twenty-four solar terms and seventy-two micro-seasons” — https://kobe-kaikyopark.kkr.mlit.go.jp/24s74k-2

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