Once served to emperors, this traditional fermented fish is quietly making a comeback
From the late 7th century, Wakasa was one of three Miketsukuni, areas designated by law to provide seafood to the emperor and imperial court. The port of Obama, nestled between mountains and the sheltered waters of Wakasa Bay on the Sea of Japan, was Wakasa’s center of supply.
From this closest seaport to the capital, porters would carry salt, seaweed, and salted fish in baskets tied to their backs directly across the rugged mountains to Nara and Kyoto. This route, known as the Saba Kaidō, or Mackerel Highway, owes its name to the abundance of mackerel in Wakasa Bay. This bounty was due to the bay’s ideal environment, created by the convergence of the warm Tsushima Current from the south and the cool Liman Current from the north.
The 72-kilometer journey from Obama to Kyoto along the Mackerel Highway took just enough time for the preserved fish to reach its optimal flavor. Seafood from Obama was highly valued in Kyoto as “Wakasa food,” and one popular dish, saba-zushi—sushi rice pressed with a fillet of salted and pickled mackerel—is still a popular washoku today and a feature of Kyoto’s annual Gion festival.
Among the foods sent to Kyoto in bygone days, one stand-out is a unique type of preserved mackerel known as Heshiko.
Heshiko
Inland along the northern section of Obama lies the hamlet of Tagarasu, meaning “crows in the rice paddies.” In one of its quiet valleys, surrounded by green mountains and picturesque rice terraces, stands a disused elementary school. Once alive with the laughter and chatter of energetic children, its classrooms fell silent more than a decade ago. Today, its schoolyard is occasionally used by elderly locals who gather for a leisurely game of gateball.
But in recent years, the school building has gained a new purpose. Its once lively classrooms are now home to hundreds, yea, thousands, of silent inhabitants—mackerel.
Tagarasu is where I was fortunate to learn about Heshiko, an ancient technique that uses salt and fermentation to preserve fish. Born out of necessity, this method helped Obama fulfill its role as a Miketsukuni, furnishing high-quality seafood from Wakasa Bay to the imperial cities of Nara and Kyoto along the “Mackerel Highway.” It also provided a vital source of protein for people living in the mountains, ensuring they had healthy food to carry them through the harsh winter months when deep snow made fresh supplies scarce.
Today, heshiko remains a local delicacy, rich in umami. Its preservation process involves salting and fermenting fish — usually mackerel, sometimes herring — for over a year.
The process begins in autumn with a fresh catch of mackerel. The fish are gutted and cleaned, their cavities filled with salt, and then they are packed into large cedar barrels.
Once a barrel is full, the fish are covered, and a two-kilogram weight is placed on top. A day or two later, the fish are removed, packed in fresh barrels, and pressed with a heavier weight. This process continues, with the weight gradually increasing, until excess liquids are removed from the fish.
When the fish are sufficiently moisture-free, they are repacked into barrels—this time filled and layered with rice bran instead of salt. Togarashi peppers are added to deter insects, and sturdy straw ropes are tied tightly around the barrel rims to seal the containers.
Left undisturbed for about a year, the mackerel undergoes slow fermentation. The following winter, the fish have transformed into heshiko and are ready to be eaten.
Heshiko is packed with nutrition and is a rich source of protein, calcium, iron, dietary fiber, EPA, DHA, beneficial enzymes, and vitamins B and D. The family of heshiko producers I met hope that one day, heshiko will be recognized as the superfood it is and that Tagarasu’s heshiko will become a household name.
Heshiko goes well with a cup of dry sake or beer. It can be served in all kinds of ways—thinly sliced atop a wedge of daikon radish, grilled, as sushi, or in chazuke — topping on a bowl of rice with green tea poured over it.
Narezushi
Some heshiko are fermented further and made into narezushi—the earliest form of sushi. To make this, the fish are first rinsed to remove the rice bran, then skinned and soaked in water to draw out excess salt. Next, they are filled with rice and koji mold — Aspergillus oryzae, the same spores used to make sake, soy sauce, and miso paste — and packed back into barrels with more rice and koji.
A weight is placed on top, and the mixture is left to ferment for a couple of weeks. After this, the narezushi is ready to eat.
Like many fermented foods, narezushi is an acquired taste and is best served in small portions. It is not nearly as salty as heshiko, and I can see how it would be a popular snack to nibble on with sake or beer.
If you’re in Japan but can’t make it up to Obama, you can order heshiko online from https://www.kadono-heshiko.com/. Unfortunately, Kadono-san cannot ship internationally.
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