The call reaches you before the smell does. A recorded voice drawls ishi-yaki imo from a loudspeaker on a small truck crawling down a Tokyo side street, and a moment later comes the scent of scorched sugar and woodsmoke. In the back is an oven lined with hot stones, and the sweet potatoes come off it with golden flesh and split skins, too hot to hold without their paper bag. The trucks' return is as good a sign as any that November has arrived, and with it a very good month to eat in the city. Days are mild and often clear, with highs around 17°C, which is exactly the weather for a sweet potato on a park bench.
The ginkgo trees that line so many streets turn gold in the second half of the month, and they drop something to eat as well. Their fallen fruit smells frankly of rancid butter, but inside is ginnan, the ginkgo nut, which izakaya roast and salt as a drinking snack, chewy and faintly bitter, with translucent green flesh. For the trees, go to Icho Namiki at Meiji Jingu Gaien, an avenue of ginkgos about 300 metres long that tends to peak in late November and carpets the pavement into early December. Most years the Jingu Gaien Ginkgo Festival sets up beside it from mid-November, with stalls selling regional food from all over Japan. Walk the length of the avenue first, then come back to the stalls for lunch.
In Asakusa, Otori Shrine holds Tori-no-ichi on the days of the rooster in the traditional twelve-day zodiac cycle, which fall two or three times each November. The fair runs for a full day from midnight, with stalls selling kumade, bamboo rakes decked out to rake in luck for the year's business, and food stalls packed around them. Look for kirizansho, the fair's speciality: strips of soft rice cake flavoured with sansho pepper, sweet with a slight tingle. The dates move every year, so check them, and take a jacket if you go after dark, when evenings cool to around 8°C.
Autumn also brings shinmai, the year's new rice, plumper and moister than the old crop, and restaurants and onigiri shops put up signs to say it has arrived. Order it plain. A salted rice ball with nothing inside is the clearest way to taste the difference, and any filling only gets in the way.