Noto Ishiru and Ishiri Manufacturing Technology

What Are Ishiru and Ishiri?

Ishiru and ishiri are types of gyoshō (fish sauce), made by fermenting seafood with salt for an extended period—usually one to two years, sometimes longer. The names are largely interchangeable and vary by district. Along the outer coast (Sotoura), which faces the Sea of Japan, producers traditionally use sardines and mackerel landed at ports such as Wajima and Takojima. Along the inner coast (Uchiura), which faces Toyama Bay, the prized ingredient is the viscera of Japanese flying squid landed at Ogi and Ushitsu ports in Noto Town.

The word "ishiru" is thought to derive from "io-shiru"—a combination of an old Japanese word for fish ("io") and "shiru" (broth or juice)—which over generations softened into ishiru and ishiri. Alternative regional names include yoshiru and yoshiri.

Alongside shottsuru from Akita Prefecture (made from sandfish) and ikanago shoyu from Kagawa Prefecture (made from sand lance), ishiru and ishiri are counted among Japan's three great fish sauces. In March 2024, ishiri and ishiru also received Geographical Indication (GI) protection from the Ministry of Agriculture, Forestry and Fisheries, further securing their place in Japan's gastronomic heritage.

A Tradition Born from Sea, Salt, and Patience

The exact origins of ishiru are unclear, but written and oral records suggest production was already established in Noto by the latter half of the eighteenth century. The Noto coast has long been blessed with abundant fish—warm and cold currents meet just offshore, creating one of the richest fishing grounds in the Sea of Japan—and the peninsula has an equally long history of salt production using the agehama-shiki method, another nationally designated technique. With plentiful fish and locally made salt at hand, coastal communities turned the parts of the catch they could not sell fresh—internal organs and small fish—into a precious, long-lasting condiment.

Before soybean-based soy sauce became widely available, ishiru and ishiri were the principal seasoning of the region. In mountain villages too remote to easily obtain fresh fish, farmers reportedly bartered rice for jars of ishiru, treating the umami-rich liquid as a treasured pantry staple. During the food shortages of the Second World War, the sauce briefly flourished again as a substitute for soy sauce.

How Ishiru and Ishiri Are Made

The production process is elegantly simple in its ingredients—just seafood and salt—but demanding in its patience and timing. Producers begin in late autumn or early winter, layering whole sardines or squid viscera with salt (roughly thirty percent of the raw material's weight) in large wooden barrels or tanks. The cold winter temperatures suppress harmful bacteria while the catch's own enzymes begin breaking down proteins.

As the seasons turn and the warm, humid Noto summer arrives, fermentation accelerates. A dark, reddish-brown liquid gradually settles to the bottom of each barrel. After at least a year—often two, and sometimes three or more for premium grades—the liquid is drawn off through a tap at the base of the barrel. It is then boiled, filtered, cooled, and bottled. Some producers in Noto Town extend the aging period by an additional year or two to develop a mellower, rounder flavor.

Although the steps sound straightforward, each producer's microclimate, barrel, and proportion of ingredients yields a subtly different sauce. The result is a rich diversity of flavors across the peninsula—a living encyclopedia of regional fermentation know-how.

Why It Earned National Designation

When the Council for Cultural Affairs recommended ishiru and ishiri for registration in early 2023, it praised the technique as "one of Japan's representative fish sauces" and noted that "the manufacturing technique, which makes use of the natural fermenting power of the raw materials themselves, exhibits pronounced regional characteristics." The council also emphasized that the traditional method of long-term aging has been carefully maintained, making the technique invaluable for understanding both the evolution and the regional diversity of fermented seasoning production across Japan.

The designation does more than honor history. It draws attention to a craft that, like many traditional food techniques, faces real challenges. Production declined sharply through the mid-twentieth century, and even today fewer than twenty active producers continue the tradition. Recognition at the national level is a significant step in supporting the small, family-run workshops that keep this heritage alive.

Tasting Ishiru: Dishes to Try in Noto

The most famous and atmospheric way to enjoy ishiru is the ishiru-no-kaiyaki, a local specialty cooked on a large scallop shell over an open flame. Squid, mushrooms, tofu, green onions, and seasonal vegetables are simmered directly on the shell with a splash of ishiru, releasing an aroma that captures the very essence of the Noto coast. The dish appears on the menus of traditional inns and seafood restaurants throughout the peninsula.

Another beloved preparation is ben-zuke or ishiri-zuke, pickled daikon radish or cucumber soaked in diluted ishiru. The pickles develop a deeply savory edge unlike anything achievable with regular soy sauce. Ishiru also features in sashimi dipping sauces, simmered seafood dishes, hot pots, and—more recently—in fusion creations by chefs who use it as a secret ingredient in everything from pasta to risotto. Its high concentration of free amino acids, particularly glycine and glutamic acid, makes it a powerful umami enhancer that pairs beautifully with both Japanese and Western ingredients.

Where to Experience the Tradition

The Noto Peninsula offers several gateways for travelers curious about ishiru and ishiri. The town of Wajima, famous worldwide for its lacquerware and its lively morning market, is also a key center of sardine-based ishiru production. Noto Town, on the Toyama Bay side of the peninsula, is celebrated as the heart of squid-based ishiri, with Ogi Port handling some of the largest landings of flying squid on the Sea of Japan.

Many producers operate small workshops or attached shops where visitors can sample different vintages, learn about the process, and purchase bottles directly. Local restaurants, inns, and roadside stations (michi-no-eki) showcase ishiru in tasting menus that highlight its versatility. For travelers planning a visit, please note that the Noto Peninsula was significantly affected by the Noto Peninsula Earthquake in January 2024 and recovery is ongoing. We encourage you to check the latest travel information from local tourism offices and producers before your trip, and to support the region by visiting open businesses when conditions allow.

Beyond ishiru itself, the Noto region offers visitors a wealth of cultural treasures: the dramatic Senmaida rice terraces overlooking the sea, the agehama-shiki salt farms still operating along the Suzu coast, the world-famous Wajima morning market, and countless seasonal festivals rooted in fishing-village life. The entire Noto Satoyama and Satoumi landscape is recognized by the United Nations as a Globally Important Agricultural Heritage System, reflecting a centuries-long harmony between people, sea, and land.