From the Choshi region to the Kujukuri region center, the Kaiso region, and the Sanbu region

Seaweed (kotojitsunomata)

Kotjitsunomata, which is the origin of "Kaisou," is a seaweed about 20 cm in height that adheres to rocks in the intertidal zone. It grows in a regular pattern, branching out in two halves. It is said that its name comes from the shape of its branches, which resemble the strings of a koto (Japanese zither). The seaweed is thickened when heated and coagulates when cooled, and was used as a soap and adhesive in the olden days. At the end of the year, merchants from Choshi sold kotojitsunomata for the New Year, and this is how it came to be used in osechi dishes.
It is customary to eat refreshing "kaizo" on New Year's Day, in addition to the more flavorful osechi dishes, to improve the digestion of the stomach. In some areas, it is also used for the Obisha Festival held on the small New Year's day.

At the end of the year, it is prepared as an osechi dish. It is an essential dish for the New Year. Because of its refreshing flavor, it is a useful chopstick rest for Osechi dishes, which often have a strong taste.

Wash kotojitsunomata thoroughly to remove dirt, then place in boiling water and simmer until thickened. When thickened, pour into molds, cool, and cut into bite-size pieces. The flavor of the sea can be fully enjoyed, so in addition to soy sauce, eat it with bonito flakes, green onions, and chili peppers on top. As an arrangement, finely chopped carrots and burdocks can also be shredded together to enjoy the different flavors and textures when eaten.

Sold at supermarkets and roadside stations under the name of "Honkaiso" or "Kaiso" (seaweed).