​At Shinnosuke Kaishin, raw clams are individually peeled, rinsed well in water to remove sand, then boiled in hot water and placed in a large pot of tamari soy sauce.
By simmering the hamaguri in tamari shoyu in a "floating simmer," in which the hamaguri float in a generous amount of tamari shoyu, they become plump and fluffy. Then, ginger is added to flavor the dish.
This process has remained unchanged since the establishment of the company, and each product is carefully worked on one by one.​