Japan's two bear species handle this differently: Hokkaidō's higuma (brown bear) digs its own den into a mountain slope, while Honshū, Shikoku, and Kyūshū's smaller tsukinowaguma (Asian black bear) more often uses a hollow tree. Both spend autumn gorging on acorns and wild grapes to build the fat reserves this stretch of dormancy depends on, then withdraw into the den right around now — driven as much by the season's collapsing food supply as by cold itself.
It isn't true hibernation in the strict biological sense, which is why Japanese carefully distinguishes 冬眠 (tōmin, deep hibernation, as in a bat or hedgehog dropping body temperature and metabolism drastically) from 冬ごもり (fuyugomori, "winter seclusion," the milder term used for bears): heart rate and breathing slow, but a bear wakes readily at a nearby sound or smell. Cubs are typically born during this dormancy, in the den's relative warmth and safety, while the mother herself stays in a light, easily broken sleep the entire time.
At or very near its true winter peak — 寒鰤 season proper, the richest stretch of the year for this fish.
Still excellent; good simply steamed or baked with a little butter and soy.
In full season, its zest essential to a winter kitchen.
Full season across late varieties, good simply as is or baked into a warm dessert.
At peak sweetness, unavoidable and essential in nabe cooking now.
Deeply flavorful now; classic long-simmered in oden or a miso-based nabe.
Still good, its slight bitterness balancing a rich winter broth well.
Both continue from the previous kō, now the season's main source of color in a garden that otherwise reads almost entirely grey and green — red berries doing in December roughly the visual work flowers do the rest of the year.
The practice of sending gifts to people one is indebted to — bosses, clients, relatives, teachers — traces back to offerings once made to toshigami, the incoming year's deity, by married-out daughters and branch families sending supplies home to the main household. That likely dates to at least the Muromachi period; Edo-period merchants making seasonal rounds to thank patrons cemented it into something closer to today's practice, and it took its modern, mostly secular shape only around the 1950s. December is dense with these overlapping year-end obligations — gift-giving, cleaning, gratitude calls — arriving in the same weeks the natural world outside is doing the opposite and shutting down.
"True hibernation" — The stricter biological term Japanese deliberately withholds from bears — reserved for animals whose body temperature and metabolism drop sharply and who don't rouse easily, unlike a bear's comparatively light 冬ごもり (fuyugomori) sleep.
蟄 (chitsu), meaning to hide away or lie dormant, is the same character used in 啓蟄 (Keichitsu), the March solar term whose own third kō describes hibernating insects opening their door back up. This kō and that one are a matched pair across the calendar's full turn — one character, used once for something going still and once, half a year later, for the same thing stirring.
Higuma (brown bear) dig their own dens into mountain slopes, sometimes reused year to year — a physically larger project than the tsukinowaguma's more common choice, further south, of simply occupying an existing tree hollow.
A denning bear wakes easily and isn't in true deep hibernation — trail and park advisories generally still apply through winter, contrary to intuition, so worth a look before you set out.
Human life doesn't get a fuyugomori built in the way a bear's does — but you can build a small one deliberately, the same way you'd block out any other appointment.
"Winter in seclusion — when spring finally comes round, the birds that stayed silent come and sing again, the flowers that hadn't bloomed bloom too..."
Department stores and delivery services get significantly busier in the final week before New Year — earlier ordering usually means more reliable delivery dates.
If you've been waiting for peak buri season, this is close to the actual top of it before it edges past its prime toward late winter.
冬ごもり (fuyugomori) was already an old, fixed poetic word for "winter" itself by the time Nukata no Ōkimi used it here — centuries before this kō borrowed the same phrase for what bears specifically do. The same character, 蟄, shows up in spring's 蟄虫啓戸 (Sugomori mushi to o hiraku, "hibernating insects open their door"), the seventh kō of the whole calendar — one kō for the door closing, another, five months and forty-six kō later, for it opening again. What door have you shut for a season, with no plan to open it yet, but full confidence that eventually you will?