It is a winter food here, which is the first thing that has to be explained to anybody from anywhere else. Snow outside, everybody with their legs under the heated table, and what gets passed around is a cold, wobbling slab of sweet bean jelly.

It is sold as a single sheet poured into a shallow paper box, uncut, with a small wooden paddle tucked in at the side. You do not portion it out onto plates. The box goes into the middle of the table and people take turns scooping along the scored lines with the paddle, which is why it is a difficult thing to eat alone.

Both the sugar and the agar are kept low, so it is barely sweet and it does not hold its shape the way a firm yokan does. It slides. It is nearer to a drink than to a confection, and a whole box goes down considerably faster than anyone intended.

None of this is treated as a delicacy locally. It is an everyday sweet, the one people here would name first if asked what their prefecture makes, and it costs very little. It is also called detchi yokan. One explanation points at an old verb for the kneading; another says that apprentices carried it home as a present when they were released for the new year. Neither has won outright, and for a food this specific to one prefecture that seems about right.