Keenly attuned to the cyclical rhythms of nature, Japan’s ancient koyomi almanac was organized into four major seasons that, in turn, were divided into 24 sekki (seasonal segments), which were further subdivided into 72 kō (microseasons).
This hyperseasonal method of cataloguing nature’s patterns first came to Japan by way of China in the sixth century. By the Heian Period (794-1185), the use of the koyomi was well established in Japanese daily life. Even in modern Japan, this system is referenced often — marked on calendars, mentioned in weather reports and used in marketing a wide variety of products to consumers.
The final segment of the koyomi cycle, known as dai-kan (great cold), corresponds to the period between Jan. 20 and Feb. 2 on the Gregorian calendar. It is, indeed, often the coldest time of year and comes just before the shift to spring, known as risshun — the first sekki of the new year.
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