Survey: Katsuo-bushi



Katsuo-bushi (Shizuoka, Japan)

The culture of Japan's katsuobushi, and it's unique production process.

Throughout the entire world, there may not be another food that is so hard that you cannot eat it without shaving it with a steel blade. Katsuobushi (a dried out skipjack tuna) is literally harder than rock.

The kanji for katsuo (skipjack tuna) is a combination of sakana (fish) and kata (hard), but the etymology can be traced back to ancient Japan, where the fish would ride the Kuroshio Current north during the spring, and return in the autumn, where they were then caught, dried, and eaten.

While katsuobushi is indeed a uniquely Japanese form of preserved food, as well as a crucial ingredient for the irreplaceably important dashi (Japanese soup broth), there is actually one other place in the world that has a similar type of dried skipjack: the island nation of the Maldives.

There, a raw skipjack is boiled in salt water, smoked, and sun-dried, commonly referred to as Maldive Fish, which is equivalent to the arabushi produced during the process of making katsuobushi in Japan. In Sri Lanka, Maldive Fish is smashed with a hammer and used as a seasoning for foods like curry.

A kezuriki takes an upward-facing carpenter's blade and attaches it to a small wooden box, where the shavings are taken from a small pull-out drawer below. The top-left kezuriki is an original piece from "Matsusaku Shoten" in Shizuoka. An Echigo Yoita traditional blade craftsman, Mr. Mizuno Kiyosuke reused the iron from a Meiji Era bridge as the base metal for this extremely hard yasukihagane blade (28,000 yen, exc. tax).

A predecessor to katsuobushi existed during the Yamato Chotei period in 4th~5th century Japan, but it was only in the 17th century mid-Edo Period in Tosa, Kochi that today's version of katsuobushi first started to make an appearance. Jintaro Kadoya and his son, the elder of which was a fisherman from Kishu, developed a method where they smoked the fish with firewood, which served to simultaneously dry the fish while adding flavor, and applied high quality fungus to the fish before aging it in order to bring out an umami flavor.

The Tosa Domain declared this a secret technique not to be shared with outsiders, but in the 18th~19th century they moved to Kogomori, and a former resident of Kishu, Yoichi Tosa, moved to Boshu and Izu. It is said that because Yoichi leaked the secret technique to other clans, he was not allowed to return to his homeland.

The back portion of the sliced fish is called the obushi (top), and the stomach portion is called the mebushi (bottom).

At the time, katsuobushi was considered a luxury food, and noble families from Kyoto and Osaka would use it in dashi to add an umami flavor to their boiled or soup-based foods.

During the Meiji Era, wars between producing regions broke out, which led to an overall improvement in the quality of katsuobushi. This in turn led to katsuobushi slowly entering the lives and diets of commoners. By the beginning of the Showa Period, the production of katsuobushi had even expanded to colonial territories like Taiwan and the South Sea Islands.

A postage slip from Matsusaku Shoten in Shizuoka, dated to 1893.

There are many steps in the time-consuming process of producing katsuobushi. Below is a rough outline:

1. Remove the head of the skipjack, fillet the fish into three pieces. For large fish, separate the back and the stomach.
2. Line the fish up in baskets and boil with hot water; after the fish has been boiled, remove the bones by hand.
3. Place the fish in steaming baskets and smoke them with fire, imparting flavor.

4. Scrape off any tar that has accumulated on the outside of the fish.
5. Sun-dry the fish. Once it is dry, place in a room and apply fungus. An artisan will repeat this cycle more than four times, creating the highest grade katsuobushi called hongarebushi. The fungus helps to break down the fat particles of the fish, producing a full but mellow flavor. The time required to complete these steps is approximately 120 days.

Adjustments to the blade are made by striking it with a wooden mallet.

It was once common for Japanese families to have a kezuriki (a special tool to shave katsuobushi) at home so that they could have freshly shaved katsuobushi for their dashi, but with the rise in popularity of dashi packs and powdered dashi, these once common shaving tools are now somewhat of a rarity. In order to prevent oxidization, the skipjack flakes are packaged in "fresh packs" filled with nitrogen, but the majority of these products are cheap and mainly use the arabushi described in step 3 as the main ingredient, whose flavor and fragrance pale in comparison to that of hongarebushi.

Once a pack is opened, the flavor will lessen over time, so if flavor quality is a consideration then the only real option is to use freshly shaved katsuobushi. Just like freshly ground coffee, freshly shaved katsuobushi possesses an aroma and flavor that cannot be compared to it's packaged counterpart.

"Matsusaku Shoten" is a Hamamatsu, Shizuoka based katsuobushi producer with over 220 years of history that is renowned throughout the country. The hongarebushi that shop owner Isao Suzuki carefully selects are all from Ibusuki and Makurazaki in Kagoshima prefecture. "Not only the skill of these artisans, but also the fungus that is cultivated for many years in the storehouses of these artisans, has a profound effect on the outcome of the katsuobushi" says Suzuki.

"We also carry a type of katsuobushi considered superior even within the categorization of hongarebushi. It is a type of skipjack caught on coastal waters by the traditional hook and rod fishing technique. The body is not cooled by the deep salt water, which lends itself to a soft texture and light, refined flavor. This product is highly sought after by traditional Japanese chefs.

The shop also carries a wide variety of kezuriki, the majority of which are specified and designed by Suzuki and crafted at the hands of an artisan. Expert smiths in Niigata and Hyogo hand-weld soft metals and hard alloys to create a special blade, which is then fitted onto a hard Japanese white oak base, with zelkova and kiri being used for the outer case. Some cases are coated in permission tannin for its insect and water repellant properties, and some even feature intricate engravings like Kamakura-bori.

"The artisan who forges the blade, the artisan who makes the base, the artisan who fits the blade to the base, the artisan who crafts the outer case. A single kezuriki represents the combination of each individual artisan's techniques. Some blades can be used for more than 50 years with proper care and maintenance. Real, freshly shaved katsuobushi can be served as-is on top of rice or used as dashi; regardless, it is extremely flavorful and highly nutritious. I would love for you to take the time to prepare and enjoy it."


053 452 7219
Opening Hours: 9:00-18:30
Closed: Sunday and Holiday

Survey, defined as: to examine or inspect. In these features, we will be reporting on things, people, places, or cultures that inspire us in our daily work of making products.

edit & text: Kosuke Ide
photo: Keisuke Fukamizu