Salted mackerel is sliced thin, laid on a fist-sized block of vinegared rice, wrapped in a persimmon leaf and pressed under a weight. Left for a day or two, the leaf gives its smell to the rice, and the acid and salt do the rest.

The fish came from the Kumano coast, salted on the shore and carried inland on men's backs over the mountains. From the pass at Obamine down to Kawakami took about two days on foot. By the time the mackerel reached the villages of Yoshino and Gojo, the summer festivals were beginning. That is not a coincidence so much as the entire explanation of why the dish exists at all, and why it exists in that particular month.

It was never everyday food. It was made for festival days, for the end of rice planting, for occasions when people gathered. Wrapped in a leaf the rice does not dry out, so it travels well, which mattered a great deal in country where the next village was over a ridge and the walk took half a day.

A landlocked place worked out how to get sea fish inland and then how to keep it, and the answer to both was salt and a leaf. The best part is opening the wrapper, which you do with your hands, and which smells of nothing else in the world.