Habanori is a seaweed from the Boso coast, dried. It grows through winter into spring, reaching fifteen to twenty-five centimeters long and one and a half to five wide, spatula-shaped, a yellowish brown tending to red. Harvested, it is chopped into pieces around two centimeters and laid out on bamboo racks to dry in the sun.

It was originally eaten as a substitute for asakusa nori, the familiar sheet seaweed, and it was not a prestigious one. The stuff looked misshapen and did not sell, so most of it was consumed by the fishermen who gathered it.

To use it you toast it dry in a pan or under a grill, crumble it between your palms until it is almost powder, and scatter it over a bowl of zoni, the soup eaten on new year's morning. The smell when it hits the hot broth is the thing people from Sanbu describe when they are away from home in January.

The reason it is there is a pun. Eat haba at the start of the year and you will haba wo kikaseru, throw your weight around, be a person of consequence, for the whole of it. So a seaweed that nobody would buy has become the one ingredient a new year in Kazusa cannot do without, on the strength of a pun.