Time Can Be Reset Overnight: How Calendars Shape Culture

Japan has no historical connection to Christianity, yet at this time every year the streets are given over entirely to the Christmas spirit. In practical terms, this is of course the product marketing of an industrial society—yet at its root lies a change in the calendar.

In my own view, because December 25 carried a strong association until after the war as the anniversary of the emperor's death, Christmas Day itself retained a solemn air of mourning the late sovereign—which in turn helped produce today's custom in which Christmas Eve is the livelier occasion of the two.

During the era of rapid economic growth, however, businesses decided that a single special day was not profitable enough, and so both Christmas Eve and Christmas Day were established as occasions, doubling the economic effect in pursuit of profit.

Thereafter, officials of the new government eagerly studied and adopted cutting-edge systems from the West, yet when it came to the calendar alone, they did not adopt the Western Gregorian calendar, continuing instead to use the one from the Edo period. This was because the lunisolar Tenpo calendar was more accurate than the solar Gregorian calendar. Why, then, change a calendar that had no need of being changed?

Had the government kept using the traditional lunisolar calendar, the following year, 1873, would have contained an intercalary leap month, requiring thirteen monthly salary payments to government officials for the year. Furthermore, even though the twelfth month of 1872 would last only two days, the government would still have had to pay a full month's stipend for it.

To put it bluntly, it was the state of the Meiji government's coffers that drove the Westernization of the calendar.

A calendar system was first adopted in Japan some 1,400 years ago, when Chinese calendars were brought over by people who came from across the sea. From then on, Japan continually imported and used the calendars updated one after another in China, building through them its conception of time and, beyond that, its history. This state of affairs lasted for centuries, until in the Edo period (1603–1868), out of a reaction against dependence on China, a movement arose to reexamine Japan on its own terms, and momentum gathered to create a domestic calendar.

Born out of this turn away from reliance on China, Japan's first homegrown calendar was the Jokyo calendar (1685–1755).

Updated steadily over the decades, Japan's domestic calendar at last reached the pinnacle of precision: the Tenpo calendar (1844–1872). It is a fascinating story—beginning by copying another country and, before anyone realized it, surpassing the original.

The twenty-four solar terms divide each of the four seasons—spring, summer, autumn, and winter—into six parts, giving each a name that marks the turning of the year, such as risshun (the beginning of spring), shunbun (the spring equinox), and geshi (the summer solstice). The seventy-two microseasons divide each of those twenty-four terms into three further steps. Each carries an evocative name capturing a subtle shift in nature, designed to bring the calendar into the texture of daily life.

In the Edo period, the astronomer Harumi Shibukawa carried out a bold calendrical reform, making the first attempt to rewrite the seventy-two microseasons to fit Japanese life—a decisive step toward an independent calendar. Officially adopted by the shogunate in 1685 as the Jokyo calendar (貞享暦), it revised the old Chinese-derived names to match Japan's own flora, fauna, and weather, replacing them with images familiar to Japanese eyes.

Where the Chinese markers for the spring equinox had been "swallows arrive" (玄鳥至) and "thunder begins to sound" (雷乃発声), the Japanese calendar changed them, as in the examples above, to "sparrows begin to nest" (雀始巣) and "cherry blossoms begin to open" (桜始開). Sparrows were closer to everyday Japanese life than swallows, and turning the focus to the cherry blossom felt far more immediate than the first clap of thunder.

To supplement the sense of the seasons on the calendar, Japan developed its own set of seasonal markers known as zassetsu (雑節), using them alongside the Chinese system. These include setsubun (the day before the start of spring), higan (the equinoctial week), hachijuhachiya (the eighty-eighth night), nyubai (the onset of the plum rains), and nihyakutoka (the two-hundred-and-tenth day), all of which still hold an important place in Japan's seasonal calendar today.

More concretely, farming tasks and community observances were planned around each solar term, and as farmers celebrated them year after year, the feel of the seasons was woven into their way of life.

Hachijuhachiya, the eighty-eighth day counted from risshun, was set as the guidepost for sowing seeds: with the danger of frost finally past, it served as the signal for tasks such as picking tea leaves.

For readers accustomed to the solar calendar, this may feel unfamiliar, but because the old calendar followed the waxing and waning of the moon, it fell behind the solar year by roughly eleven days every year, eventually drifting out of step with the seasons and the heavens. That is why the ancient system of the twenty-four solar terms played such a vital role as rekichu (暦注)—calendar annotations that kept track of the true season. An agrarian way of life cannot do without clear markers for when to till the soil and when to sow seeds.

Annotated onto the old calendar, the solar terms and microseasons gave rhythm to the agricultural year and determined the timing of festivals and annual observances. It was out of this systematization and Japanization of the calendar that many of Japan's distinctive festivals and annual events were born—which means that the majority of festivals still celebrated today have their roots in the harvests of an agrarian people.

Wisdom this deep, absorbed into the Japanese way of life over more than a thousand years, is not easily erased, no matter how fast modernization accelerates. That is why so many long-term visitors are astonished to find ordinary Japanese people—people who have never once studied this calendrical lore in school—living in effortless accordance with the seasons.

Yet judged by the ancient lunar calendar, which early Japan adapted from the sophisticated culture of China, the true moment for the rite has not yet arrived. This is no trivial technicality. Looked at from a deeper vantage point, mistiming the harae (祓え)—the act of ritual purification—becomes a hidden source of spiritual disquiet.

While I conform to the civil calendar in society, I personally regulate my physical and mental equilibrium through what I call a "dual calendar system," dwelling within a temporal space where I gauge my inner state by the lunar rhythm. Observing the chronic exhaustion of contemporary Japanese society, I am convinced that moving fluidly between these two temporalities is indispensable for navigating modern life and sustaining one's reiryoku (霊力), or spiritual vitality. The causes of Japan's modern malaise are multifaceted, but I locate one of its deepest roots in this temporal schism: a national spirituality torn between two irreconcilable calendars.

What has changed is not merely the seasons, but the very environment in which human beings live—and that means the rules of survival have changed. If so, we may no longer possess the inner room we once had, the room required to nurture culture.

Gradually, everyone is driven into a harsh, competitive struggle for survival, forced to focus simply on keeping oneself and one's loved ones alive. In fact, I feel that Japan has already entered that stage.

From four seasons to two: 2024 was a year in which I felt the unmistakable tremors of a world about to change completely.