The swallows that arrived in spring have finished raising their young and slipped south again; in their place, geese begin arriving from Siberia and Kamchatka to spend the winter in Japan. This kō is the mirror image of 鴻雁北 (Kōgan kaeru, "wild geese return north"), the second kō of Seimei in early April — together the pair frame the geese's entire year, one candid line drawn from spring to autumn and back. Watch the sky in the early morning or at dusk and you may catch a skein of them, flying in a loose V or diagonal line, calling to each other in a thin, carrying cry that classical poets found almost unbearably plaintive.
"雁" (gan/kari) is not one species but a catch-all term for several kinds of migratory geese — in Japan mostly the greater white-fronted goose (真雁, magan), a grey-brown bird a little larger than a mallard and smaller than a swan (鴻, kō, in the kō's name refers to the swan-sized end of that spectrum). Roughly 80% of the magan that winter in Japan concentrate in just three wetlands in Miyagi Prefecture — most famously Izunuma-Uchinuma, a Ramsar-listed marsh where the evening flight of tens of thousands of geese lifting off the water at once is one of the country's great unscripted spectacles.
At its fattiest and most celebrated in early-to-mid autumn; the classic preparation is simple shioyaki with grated daikon and a squeeze of sudachi.
Autumn-run salmon head upriver to spawn now — leaner than farmed salmon, with a firm texture suited to nabe and shioyaki.
The start of the raw-oyster season proper — months with an 'r' in them, as the old saying goes, though Japan's oyster calendar runs a little differently by region.
October is peak season for both sweet (甘柿) and astringent (渋柿) varieties — the latter dried into hoshigaki over the following weeks.
Crisp, juicy, and far less sweet than Western pears — best served well chilled, cut into wedges.
Late-season varieties like Kyohō reach their peak now, deep purple and thick-skinned.
Harvested through autumn; roasted whole (焼き芋) from a street cart is one of the season's small pleasures.
Sticky-textured and mild, classically simmered in a soy-dashi broth alongside chicken or pork.
Named 'dancing mushroom' for the joy foragers supposedly felt on finding one — good torn by hand and grilled or fried in tempura.
Roasted in their shells until they pop, then shelled and lightly salted — a classic autumn izakaya snack, best in small quantities.
Kinmokusei's small orange clusters are easy to miss by eye but impossible to miss by nose — its sweet, apricot-like scent can carry down an entire street, and then is gone again within a week or two. There's a small, well-loved melancholy in how briefly it lasts each year; more than one Japanese writer has noted that you never quite remember the smell precisely enough between one October and the next, so it always arrives as a surprise.
Where 十五夜 (jūgoya), the mid-autumn full moon, was a custom imported from China, jūsan'ya — moon-viewing on the 13th night of the ninth lunar month, when the moon is not quite full — is considered uniquely Japanese in origin. It falls close to this kō most years and is also called 栗名月 (kuri-meigetsu, "chestnut moon") or 豆名月 (mame-meigetsu, "bean moon"), for the chestnuts and edamame traditionally offered alongside tsukimi dango. Viewing only one of the two moons — jūgoya or jūsan'ya — without the other was once considered bad luck, called 片見月 (katamizuki, "one-sided moon-viewing").
"The wind that carries the geese across" — A classical autumn kigo for the steady north wind that blows around the time the geese arrive from the continent — cool, clear weather that also clears the summer haze from the sky, sometimes called 青北風 (aogita, "blue north wind") for the deep blue it leaves behind.
鴻 (kō) denotes the larger, swan-sized end of migratory waterfowl; 雁 (gan/kari) the smaller, duck-to-goose-sized end — together the name covers the whole spectrum of migratory geese arriving at once, without specifying a single species. In Japan the word survives in an unexpected place: がんもどき (ganmodoki), the fried tofu fritter found in oden, whose name literally means "mock goose" — an old vegetarian approximation of goose meat, developed for Buddhist monks who couldn't eat meat but still wanted the flavor.
Roughly 80% of Japan's wintering greater white-fronted geese (magan) concentrate at just three wetlands in this one prefecture — Izunuma-Uchinuma, Kabukurinuma, and Kejonuma — with Izunuma-Uchinuma registered as a Ramsar wetland since 1985.
Geese fly in a loose V or diagonal line, calling to keep the formation together — most visible at dawn or dusk as they move between feeding and roosting grounds.
The Thirteenth Night moon falls on a different date each year (it follows the old lunar calendar) — worth checking so it isn't missed after already having viewed jūgoya.
"From today, you are Japan's own geese — sleep easy now."
The 雁渡し wind marks a real, lasting drop in temperature, not a passing cool snap — a good point to swap in autumn-weight futons and blankets.
Satsuma-imo is at its most abundant and least expensive right now; roasting a whole batch and refrigerating keeps them ready for a quick snack all week.
The geese arriving now flew from Siberia or Kamchatka without a single stop, reading a route none of them had personally flown before — young birds follow the adults, and the whole skein reads the wind and the stars together. Issa's haiku welcomes them with something close to relief: the hard part is over, rest now. What in your own year has just landed, and deserves that same permission?