Shellfish
Whelk (Tsubugai)
【Nigiri sushi: Kai】
Whelk (Tsubugai) is a general term for several species of marine snails that are popular in Hokkaido and the Tohoku region. Among them, Ezo-bora (also known as Ezo-bora-modoki) is a high-quality sushi topping characterized by its cream-colored flesh and pronounced sweetness. At Toyosu Market, it is also known as “Matsubu.”
It has a pleasant, crunchy texture when you bite into it, and as you chew, a subtle bitterness without any unpleasant aftertaste, along with a delicate sweetness, gradually spreads across the palate. Its appeal lies in the distinctive way it allows you to appreciate the natural, briny character of shellfish, setting it apart from other varieties.
On the other hand, in the Kanto region, some sushi chefs believe that its distinctive texture makes it “better suited as an appetizer than for nigiri sushi.” As a result, opinions among chefs are divided: some choose to use it for nigiri, while others prefer not to.
Although Tsubugai is generally eaten raw, it is also delicious when cooked and does not become tough. In Hokkaido, “Tsubuyaki”—Tsubugai grilled and seasoned with soy sauce—is a beloved local dish and an excellent example of how cooking can bring out the shellfish’s natural umami.
However, some species of Tsubugai contain a mild toxin called tetramine in their salivary glands. Accidental ingestion of the toxin can cause symptoms of poisoning, including dizziness and visual disturbances. If preparing Tsubugai yourself, great care must be taken to remove the salivary glands completely.
【What is Tsubugai】
Tsubugai (Whelk) is found all the way from Hokkaido northward and to the Bering Sea. It mainly inhabits the sand and gravel of shallow seas up to 10 meters deep from the tidal zone. It has a thick and robust shell that grows to heights of 15 cm and a width of 10 cm. The shell’s surface is a slightly reddish-brown color.
【Related contents】
What is Tetramine poisoning?
What is Baigai sushi?
List of Shellfish (Kai)
(Revision date: August 13, 2026)