The origin of umami, born from the ancient sea and man - Ichimaru's journey to recreate ancient Katsubushi

Yaizu Port bathed in the soft winter sunlight.
Yaizu has long been known as one of Japan's leading bonito producing areas, and since the Edo period, it has been famous throughout the country for its "Yaizu bonito flakes."
The scent of the sea and the fragrant aroma of bonito wafting from the nearby processing plant blend together, quietly telling the story of this area's long history as a "bonito town."

"It seems that bonito was a special fish for the Japanese."

These are the words of Honda, who is attempting to recreate ancient katabushi at Ichimaru, a long-established fishery company in Yaizu.

He told us about the katsuogi (bonito sticks) seen in shrine architecture.
Katsuogi is now known as a design element for shrines, but the Nihon Shoki also contains myths surrounding it.
Bonito had such a special meaning to ancient people that it appeared as a symbol of wealth and power.

The beginning of the project: "Recreating ancient offerings"

Fifteen years ago, in 2010, the Heijo Capital 1300th Anniversary Festival was held to commemorate the 1300th anniversary of the transfer of the capital to Nara. As a related event, a project to "recreate ancient tributes" was launched in collaboration with local industry, academia, government, and finance, centered around the Yaizu Bonito Flakes Seafood Processing Cooperative, in order to reexamine the history and traditions of Yaizu bonito flakes. The Shizuoka Prefectural Fisheries and Marine Technology Research Institute and a Yaizu bonito flakes manufacturer were involved in the experiment to recreate "nikatauo" (boiled hard fish).

"At first, I thought it was interesting, but as I looked into it, I began to think that ancient preservation techniques were far more efficient and efficient than modern standards could ever imagine."

This initiative was a one-off event, but the experience left him with the question, "Is it okay to let this knowledge end here?"

At the same time, a university research team was conducting research on ancient foods, focusing on bonito, and an opportunity arose to exchange opinions with the researchers.
Through repeated conversations, they realized the importance of not just relying on literature but actually making and verifying the product, and decided to once again work on recreating processed bonito products as Ichimaru.

Information about ancient manufacturing methods is fragmentary in written documents, and there are many parts that we have to rely on imagination.
However, Honda worked in collaboration with researchers in culinary history, archaeology, and fermentation science, and through repeated verification, he constructed a method that people at the time could actually use.
It was this accumulation of trial and error that led to the current reproduction of "ancient Katsubushi."

"Shizuoka's bonito culture is not just about modern bonito flakes. It has a much deeper history that dates back to ancient times—that's what I realized at that moment."

Ancient "bonito processing" revealed through documents and pottery

Recreating ancient Katsubushi is not just culinary research.
It is a steady and grand undertaking that involves repeated "experiments" while interpreting archaeological materials, ancient documents, excavated pottery, and the climate of Yaizu one by one.

Honda consulted with several curators knowledgeable about ancient pottery in order to create a replica of pottery from the Nara period.
Based on this knowledge, they commissioned a potter who had studied ancient pottery to create earthenware for cooking.
Furthermore, with the cooperation of experts, they also worked to recreate earthenware that is believed to have once been used to hold broth, using soil from the upper reaches of the Seto River in Fujieda.

"There are many things that you can't understand just by reading about them, so I try them all out. It's a matter of 'testing, not imagining,'" says Honda.

No one knows how ancient people adjusted the salt content, how they boiled it, and how they dried it.

That is why Honda carefully studied documents, pottery, and excavated materials, listened to experts, and tested each of the hypotheses he came up with through experiments.

The thickness and shape of the pottery to withstand fire, the height of the rim to prevent the broth from spilling even when boiling, the existence of tools to pull the fish out of the boiling water, the processing system that is thought to have been used for mass production on the wide beach... All of this is compared with the documents and recreated by hand.

"The wooden tablets contain records of processed bonito products containing the equivalent of thousands of fish per year. Fishing alone would not have been enough to keep up with the demand, so they must have captured the cycle in which the bonito came near and processed them on an industrial scale all at once."

Using only pottery, seawater, and firewood, we attempt to process the material under conditions similar to those of ancient times.
This steady accumulation of efforts gradually brought to life the landscape of 1300 years ago.

Verifying ancient wisdom with your own hands: A track record of on-site verification

The basic method of ancient Katsubushi is to "boil in seawater and dry."
It sounds simple, but it's surprisingly difficult to do in practice.

First, the bonito is cut into pieces and placed in a large earthenware pot, where it is boiled in seawater. The salt in the seawater enhances the preservation time and prevents spoilage, making this a particularly important technique in ancient times, when there were no refrigerators.

The most ancient and difficult process is drying the boiled bonito in the sun.
Honda kept a close eye on the bonito dried outside, keeping an eye on the weather and sea breezes every day. On some days, the temperature of the sand rose to 52 degrees, and he also had to deal with the constant battles with crows.

I moved my desk outside and continued testing, even though my coworkers laughed at me and said, "You're drying it out again today..."

This is how it is completed"Nikatauo" (stewed hard fish).

The subtle differences in wind, sunlight, drying angle, and humidity affect the taste and shelf life of the product. These "fluctuations" that cannot be replicated by artificial drying are the true value of the ancient method.

On the other hand, the full picture has not yet been revealed."Katsuoirori (hard fish decoction)"
This seasoning is made by further reducing the broth used to boil bonito, increasing the salt content from 3.5% to about 15%, ensuring its shelf life.

It is thought to be similar to hishio (a type of soy sauce) and was used as a seasoning alongside salt, sake, and vinegar, and also in kan (a type of hot soup).

"Considering that it was used in imperial court cuisine, it cannot have been a muddy liquid mixed with bonito dregs. I think it was probably filtered through hemp or something to create a smooth liquid."

This is Honda's hypothesis, based on the shape of the jar and the method of transportation.
Although its shape is still under research, therein lies the "interesting aspect of unraveling the ancient past."

How will "ancient flavors" change modern cuisine?

"Ancient Katsubushi" was born from accumulated research.
When I actually tasted the commercial version, the difference was clear.

"Ancient katsuobushi is not smoked, so it doesn't have the smoky flavor of modern katsuobushi. Only the pure umami flavor of the fish remains."

The aroma of bonito spreads the moment you open the bag.
When you put it in your mouth, the saltiness and umami of the fish rise directly, and the lack of a smoky aroma gives it a clear taste. It's not a flashy taste, but it leaves an indescribably deep aftertaste that conveys the message of the ingredients directly.

If you learn about the history and the journey that went into recreating it, you may find it even more enjoyable.

"Just as there are dishes that go well with arabushi, there are also dishes that do not require a smoky aroma. Kodai Katsubushi goes very well with dishes that bring out the flavor of the ingredients."

How can modern chefs use this "ancient umami" in their cooking? This opens up new possibilities.

History, geology, family crest... the land of Yaizu itself speaks volumes

During the interview, Honda's topics of conversation were not limited to food.

He talks about geology, iron production, and even his own family crest.
The origins of the land of Yaizu, the clay used for pottery, and the culture of using fire.
Everything is connected to the "Ancient Katsubushi."

"The character for 'yaki' (burn) is in Yaizu, right? It's possible that this area has had a deep connection with fire since ancient times."

"Fire," "earth," and "sea" are essential elements for making dried bonito flakes in ancient times.
It was precisely because these resources were available in this region that the ancient bonito processing culture developed.

Fujieda, Yaizu, Izu...

Pottery excavated from each region indicates that bonito processing was widespread.
Listening to Honda's story, it was as if an ancient seaside was unfolding before my eyes.

The future of ancient Katsubushi: Food culture enters an era of "rediscovery"

The ancient Katsubushi is not simply a replica, but a new cultural resource of Shizuoka.
The possibilities are endless, including Man'yoshu food events, collaboration with museums, use in restaurants, and experiential courses.

Because mass production is difficult, there are limited places where it can be purchased, but in the future the company is considering processing it in a way that makes it easier to handle and establishing a system for doing so.
Currently, it is only available for sale online and at Ichimaru Marche.

However, Honda says:
"First of all, I want people to know that these products are made in Shizuoka. That's the first step. We need a place where we can talk about them, not just online or in stores. I want people to understand the background before they pick them up."

It is only by savoring it alongside its history that ancient Katsubushi finally gains its "true value."
Ichimaru's challenge from Yaizu has us re-examine the question, "What does it mean to taste?"

How do modern chefs express the "taste of ancient times"?
And what kind of history will those who eat it sense from its taste? Kodai Katsubushi is not just a product, but a medium for "communicating with history through eating," quietly opening up new possibilities.

Conclusion

"Ancient food is not something to be imagined, but something to be verified."

Honda's words succinctly express the essence of this project.

Indeed, the recreation of ancient katsuobushi is imbued with passion, knowledge, an experimental spirit, and respect for the region's history. The journey in pursuit of the "lost flavor" at the origin of katsuobushi quietly awakens the cultural memories etched in the land of Yaizu. After listening to an explanation of "ancient katsuobushi," when you take a bite, you can almost picture the sea breeze of over a thousand years ago and the activities of ancient people.

It is a special experience that allows you to experience food culture across time.
I want people who visit Yaizu, the fishing town, to know this story.
Behind the ancient katsuobushi lies the wisdom of people who have lived with various marine resources, including not only bonito but also tuna, mackerel, sardines, and other fish, and a long history of interacting with the sea.

The wind blowing through the harbor, the fragrant aroma lingering in the processing plant, and the fishing culture that lives on in the town.
All of these are the very memories of the people who have lived in this land and with the sea.
If you walk around Yaizu after learning about the ancient Katsubushi, the town's scenery will look completely different.

The fish lined up in front of the shops, the people working at the port, a piece of sashimi on the dinner table - behind each of these scenes, the ``ocean and human activities'' that have been passed down for over 1300 years come vividly to light.

A trip to Yaizu is not just a "food tour"
It will deepen into a "gastronomic journey tracing the culture of the sea."
The ancient Katsubushi may be a small key that will lead us to that entrance.

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Ichimaru Co., Ltd.

425-0021
2-5-13 Nakaminato, Yaizu City, Shizuoka Prefecture
TEL：054-628-2141

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Ichimaru Food Factory (Ichimaru Marche)

425-0012
1-3-23 Hamatome, Yaizu City, Shizuoka Prefecture
TEL：054-628-4115

https://yaizu-amimoto.jp

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Date of coverage: July 2025, 12

Writer: Masako Omura

Photo: Yoshihiko Konan