You cut it and a picture appears. A flower opening, a butterfly, sometimes a written character. The maker builds it from thin rolls of nori and kanpyo and thin omelet and rice tinted in several colors, assembling them into a larger roll the way you would set type. There are said to be more than a hundred established patterns.

It goes back in Boso to the Kansei years at the end of the eighteenth century. One account traces it to the lunch boxes carried by fishermen from Kishu who came north following the sardine runs and stayed.

The list of occasions it belongs to is long and specific. Horseback archery festivals. Seasonal festivals, the bean-throwing at setsubun, the kosaiko gathering that prays for safe childbirth, the ebisuko for good trade, the mushiokuri that walks the insects out of the rice fields. Also, now, school entrance ceremonies and sports days and cherry blossom picnics.

The thing works like a stick of rock candy: cut it anywhere along its length and the same image is there. Which means the maker is not decorating a surface. They are constructing an image through a solid, invisible until somebody takes a knife to it, and then repeated identically for every person at the table.