This is a kind of oshizushi made with masu. It is made with sliced masu which is salted and seasoned, then packed and pressed into a round container lined with bamboo leaves. It is said masu zushi was invented in 1717 with good-quality rice and ayu from Jinzu river. It was sent to Yoshimune, the eighth shogun of Tokugawa by then lord of Kaga, and Yoshimune known as a gourmet was so impressed with how tasty it was. Later the sushi was made with masu, and it has become a delicacy of Ecchu, and is popular as ekiben and souvenir. There are still many specialty restaurants along Matsu river.