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Kusaya, the Islands’ Fermented Food, Passed Down from Generation to Generation

Tokyo Islands
伊豆諸島を代表する郷土料理「くさや」

(Month information was collected: October / December 2020)

Kusaya, a fermented food representing the Izu Islands, was created accidentally while the islanders used their wits and ingenuity in a living environment unique to the remote islands. While it has a distinctively pungent aroma, some can become addicted to its rich umami. We visited Niijima and Hachijojima to explore the roots of kusaya.

Kusaya’s secret ingredient is the kusaya brine that has been handed down for 300 years.

Niijima, which is part of the Izu Islands, is a small island about 150 kilometers south of mainland Tokyo, with 2,000 inhabitants. It is regarded as kusaya’s birthplace, and the majority of kusaya produced in Japan comes from Niijima. Six kusaya producers have survived on the island. Five of them share the use of Kusaya-no-Sato, a kusaya processing facility and distribution center, recognized as Niijima’s kusaya production base.

Ryota Ikemura, a producer who represents Iketa Shoten, taught us kusaya’s manufacturing process and history.

Kusaya’s manufacturing process is quite simple. It involves just fish, salt and kusaya brine. In Ikemura’s factory, the basement storeroom houses two kusaya brine tanks that produce the liquid with a twist of the faucet. Salt is added to the brine according to the amount of fish to be marinated to adjust the kusaya brine’s salt level. Making dried fish ordinarily requires an 18 to 20 percent saltwater solution, but Niijima’s kusaya brine is made with just an 8 percent saltwater solution.

Amberstripe scad is commonly used to make kusaya on Niijima as it can be caught in large quantities in the island’s surrounding waters. Each fish is gutted by hand on a chopping board, rinsed in water, soaked in kusaya brine for a day or two, and dried in the drying room.

While some of the dried kusaya are packaged for sale, others are pre-grilled and cut into strips to make it easier to eat for those who refrain from cooking it at home because of the pungent smell kusaya emits when grilled.

The kusaya brine determines kusaya’s flavor, commented Ikemura.

“We get tasty kusaya when the kusaya brine works its magic properly. Since the brine is like a living being, it loses its potency if left without fish for a while. Having said that, it’s also important to let it rest, so we use the two tanks on alternate days.”

Kusaya brine emits a strong aroma that stings your nose when you take a whiff up close. So, what is this mysterious liquid that makes kusaya what it is? Its story goes back well over 300 years.

It is said that the kusaya-making industry on Niijima began in the Edo period (1603–1868). Since the fish-eating islanders could not go out to fish during the stormy winter, they preserved amberstripe scads, which they could catch in abundance in the summer, by soaking them in saltwater and drying them in the sun. Since the islanders had to offer salt to the shogunate government in place of land tax, salt was the most valuable resource on the island. Therefore, the islanders had to repeatedly use the same saltwater by adding water and salt each time.

The islanders discovered that as they used the same saltwater to marinate fish, the fish’s bacteria and essence blended into the saltwater, maturing it and increased the umami and flavor of the dried fish. This is how kusaya came into being.

The saltwater solution was eventually handed down to kusaya producers and homes on Niijima as kusaya brine and has been used ever since.

“The kusaya brine we use goes back over 300 years, and we’ve been using it by adding to it each time. It’ll take 300 years to create it, and we can’t reproduce it. The number of bacteria and salt level vary by producers as we use and store the brine differently, so each kusaya brine is unique.”

Ikemura is the third head of the business, which his grandfather started. In his thirties, Ikemura is the youngest kusaya maker among the island’s aging kusaya producers. Still, he is engaged in kusaya-making daily with a firm belief, actively preparing to expand sales channels overseas.

“I have nothing but gratitude to our forefathers who left us kusaya on this island. We’re living today, thanks to them. I believe it’s my role to pass down this culture to the next generation,” commented Ikemura.

新島の風景

魚をくさや液に漬け込む工程

くさやを乾燥室で乾燥させる工程

焼いたくさやを食べやすいようにスティック状に削る工程

  • 300年以上伝承されるくさや液
  • くさやの原料となるアオムロアジ
  • 新島で長年作り続けられる「くさや」
  • 新島でくさや生産を行う池太商店の池村さん

Delivering kusaya to a wider audience through unique ideas

Kusaya-making began on Niijima, spread to the surrounding islands, and took root as a regional dish across the Izu Islands. However, in reality, the number of producers has declined due to depopulation on the islands, and people are beginning to lose interest as an increasing number of them are avoiding kusaya because of its much-publicized distinctive odor.

Under such circumstances, new blood has come forward, presenting various ideas and working to convey the appeal of kusaya to as many people as possible.

Ko Kato of Aigae Suisan is a kusaya producer on Hachijojima. A native of Numazu, Shizuoka Prefecture, Kato moved to Hachijojima when he was 23. Kato discovered kusaya in an unexpected turn of events while working in construction sites and restaurants. He began harboring a wish to produce kusaya as he became hooked on its appeal.

“I was often treated to kusaya by older local women. I wasn’t initially keen on it because of its overwhelming odor, but I got over the stench the more I ate it and started noticing the umami. I began to think that it had outstanding hidden potential.”

When Kato turned 30, a local fishery’s processing company he knew gifted him a precious kusaya brine. Day and night, he struggled with the 120-year-old kusaya brine from the Meiji period (1868–1912) and mastered kusaya-making. In the beginning Kato had a lot of trouble as the taste was unavoidably inconsistent, but he managed to control it to produce delicious kusaya after three to four years.

“I found out that kusaya depends entirely on managing the kusaya brine. Since it’s a living being teeming with bacteria, it loses vim, and its fermentation weakens unless you soak fish in it even when you’re not making kusaya. You can’t make tasty kusaya if you don’t aerate the brine and look after it constantly.”

Kato not only produces kusaya but he also promotes its appeal through various means such as opening a restaurant that serves unique kusaya dishes next to his Hachijojima factory and creating Japan’s first bar specializing in kusaya in central Tokyo, with a wish to convey to as many people as possible the deliciousness of kusaya and how to enjoy it.

“I think providing ideas for new ways of enjoying kusaya, including pizzas and ajillo, might soften people’s resistance. Just like me, I think people will come to love it, even if they feel uncomfortable at first. I want people of all ages to know what makes kusaya appealing,” commented Kato.

Kusaya is a fermented food accidentally created by reusing saltwater to save on salt out of necessity. We hope you will savor its umami imbued with the islands’ history if you get a chance.

くさや

藍ヶ江水産の加藤幸さん

くさや製造を行う藍ヶ江水産の加藤さん

食卓に並ぶくさや

Writer : TAICHI UEDA / Photographer : SHIOMI KITAURA / KOJI TSUCHIYA / YUTA SUZUKI

*Some of the images posted on our website have been provided by those whom we inter-viewed.

Iketa Shoten

Address 6-3-3, Honson, Niijimamura, Tokyo
Closed Sunday
URL http://iketa.com/
  • 池太商店の店舗外観

Aigae Suisan seafood diner

Address 2333, Okago, Hachijomachi, Tokyo.
Closed Sunday
URL http://across.co.jp/aigaesuisan/
  • 藍ヶ江水産の店舗外観

*The information in this article is current as of the date of the interview. Please contact the restaurant for the latest information.

Related Links

Tokyo Treasure Islands official website https://www.t-treasureislands.metro.tokyo.lg.jp/en/

Tokyo Tourism Information

japan-guide.com https://www.japan-guide.com/e/e2164.html
Japan Travel http://en.japantravel.com/tokyo