Off Choshi the Kuroshio coming up from the south meets the Oyashio coming down from the north, and the Tone River empties into the same water. The result is plankton in quantity, all year, and sardines in numbers that have kept this port among the busiest in the country.

The fattest of them are landed in the rainy season. Fish caught in June and July have a name of their own here, nyubai-iwashi, the rains sardine, and they are the ones the town waits for.

There is no single way of eating them, and that is really the point of the place. Raw as sashimi; grilled with salt; simmered; cooked down into tsukudani. Chopped with miso into namero, or rolled into balls for a soup, or grilled in a shell as sanga-yaki, or glazed like eel, or dressed in okara.

Around the harbour there are processing sheds, and what happens inside them is the other half of the story: salting, drying, freezing, curing in mirin, and packing. A maruboshi is the whole fish dried entire, head and gut and all, and it will keep for months without refrigeration. From one boat, on one morning, the same catch splits into something eaten raw within the hour and something that will keep for months.