Photo/IllutrationGotemba-produced wasabi priced at 24,000 yen a kilogram line a storefront. (The Asahi Shimbun)

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Editor's Note: This is the first in a two-part series of articles on wasabi (Japanese horseradish). When we discuss Japanese food, wasabi has been an indispensable foodstuff since olden times. Even in Europe and the United States, it is now common for wasabi to be used in dishes amid the booming popularity of “washoku” (Japanese cuisine). Shedding light on wasabi that has become a worldwide foodstuff as a condiment originating in Japan, we take a closer look at the influences it has given to food culture and its attractiveness.

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Selected wasabi (Japanese horseradish) are assembled in Tokyo’s Tsukiji market from throughout the country. In its vegetable and fruit sales floor, wasabi that line the storefront of long-established intermediate wholesaler Kushiya are especially conspicuous. They are priced at more than 20,000 yen (about $170) per kilogram, which is higher than tuna sold in the adjacent seafood sales floor.

This wasabi attracts customers not only in high-class sushi restaurants in central Tokyo but also overseas.

“If you know the flavors of ‘maguro’ (tuna) and ‘hirame’ (bastard halibut) served with this wasabi, you cannot eat them without it,” said Masahiro Sugimoto, president of Kushiya.

What wasabi elicits such high praise from the professional maven? We visited its producer, Keiichi Tashiro, 43, a farmer in Gotemba, Shizuoka Prefecture.


Tashiro’s wasabi fields are dotted along a river that flows between the mountains. The area has an abundance of spring water, whose temperature ranges between 10 and 13 degrees throughout most of the year. His wasabi fields take in this spring water. The fields are slightly inclined so that the water spreads equally to the entire fields. However, each field differs in size and shape. He slightly changes the field depending on such factors as the amounts of sunlight and the tilt of the land.

There are various cultivation methods, and Tashiro is adopting a method called “ishiue” (stone on). It is called that because a stone is placed on a seedling when wasabi is grown.

“Another method is ‘chon-ue,’ whose word origin is said to be ‘chokon to ueru’ (planting it slightly). In addition, there is a cultivation method of protecting a seedling from outside elements by covering it with pipes,” he said.

In the ishiue method, wasabi is laid on its side, so it grows horizontally. As a result, almost all the parts of wasabi are exposed to spring water and become bright green.


Following in the footsteps of his father, Kaoru Tashiro, 78, Keiichi began to cultivate wasabi. His career has spanned about 20 years. However, he fails even now.

In 2016, wasabi grew to only about the size of the tip of a thumb in one field. He is raising a variety called “Mazuma,” which takes about a year and a half to one year and 10 months for the wasabi to grow from seedlings to a size large enough for shipping. The period from planting the seedling to harvesting is lengthy, unlike many other agricultural products.

Because of that, it is painful when wasabi have not grown large enough to be shipped at the time of harvesting.

“I don’t know the clear reason for the failure. If my father cultivates it, he does not experience such a failure,” said Keiichi Tashiro.

What his father has that he does not have is intuition resulting from experience, which is important for growing wasabi.

According to Tashiro, three factors are indispensable for wasabi cultivation: abundant spring water, avoiding strong sunlight and soil with good permeability. Seeing the degrees in the growth of wasabi, he changes the amount of water when irrigating them, mixes soil to improve its permeability and covers the plant with black plastic sheets depending on the strength of the sunlight. These works have major influences on the growth of wasabi. And even if he continues to do the same work, wasabi does not necessarily grow as idealistically as hoped.


In September 2010, Tashiro’s wasabi fields were completely destroyed by a flood caused by a typhoon. Reminders of those days remain around the area.

“It can’t be helped because wasabi cultivation is influenced by nature,” said Kaoru Tashiro.

The Tashiros were forced to start to create wasabi fields from scratch. It took nearly six years to return the fields to their original state though Kaoru also made efforts to do so.

“As long as there are people who are waiting for my wasabi, I cannot stop cultivating it,” Tashiro said with a smile.


Masahiro Sugimoto, president of long-established intermediate wholesaler Kushiya in the Tsukiji market, has continued to purchase the Tashiros’ wasabi for more than 20 years since the days of the father, Kaoru.

Sugimoto has tasted the wasabi of almost all the major production areas, such as Izu (Shizuoka Prefecture), Nagano, Akita, Iwate and Okutama (Tokyo).

Among these, Sugimoto “fell in love” with Tashiro's wasabi.

“His wasabi is especially delicious and its appearance is also good.”

Sugimoto doesn't fall in love with wasabi unless it scores nearly complete points in all five categories of hue, aroma, adhesiveness, hot flavor and sweetness.

“Delicious wasabi becomes a fresh green color when it is grated. Its pungent aroma is also distinctive. It also has adhesiveness and has a strong, hot flavor. There is also a delicate sweetness that comes after a while. The biggest difference between Tashiro's wasabi and other wasabi is sweetness,” Sugimoto said.

Even among Tashiro's wasabi, there is a difference in prices shown by Sugimoto. The cheap ones are priced between 6,000 yen and 8,000 yen per kilogram while the best ones are priced at more than 20,000 yen. According to Sugimoto, the best wasabi are different in appearance, and he calls them “handsome.”

The characteristics of the appearances are as follows: They are straight in shape and have few convex or concave portions on their surfaces. The color of their stems is purple. The bumps, which are traces of leaves that fell, are the same. The distances between spiral lines that can be found if seen up close are also equal.

“Handsome wasabi are extremely delicious. If they are not so, I cannot show prices that are four times higher than those of conventional ones,” Sugimoto said.

Wasabi he has purchased from Tashiro are mostly sold out within a week. A chef has even traveled from New York to buy the wasabi from Sugimoto.

The Kushiya president believes that wasabi plays a role in enriching Japanese food culture.

“Wasabi is not a main ingredient in sushi or sashimi (slices of raw fish). In addition, it is free of charge when offered in restaurants, though it is more expensive than most of the main items when purchased. Despite that, there are chefs who recognize its value and buy it. That is because there are customers who seek it out,” he said.

He added, “There were times when customers said, ‘Give me tears' when they ask for wasabi in sushi restaurants (because wasabi is so pungent that they often shed tears when they eat it). If they say so, chefs would be able to understand that. Such a play on words was born, which promoted communication. I think that wasabi also has such a power.”


Takeo Sato, 45, manager of sushi restaurant Tsukiji Sushiko Jin, in Tokyo’s Akasaka district, also fell in love with Tashiro’s wasabi. He has continued to utilize it since the opening of the restaurant in 2011. He began to buy it under the recommendation of President Masahiro Sugimoto of intermediate wholesaler Kushiya. Recalling when he tasted it for the first time, Sato said, “The adhesiveness, aroma and taste that were produced when the wasabi was grated all harmonized with each other. They were completely different from ones I had tasted.”

Reactions from customers are also good. Some customers ask chefs to serve the wasabi on different plates so that they can adjust the size of the wasabi by themselves.

“When I serve wasabi in that manner, customers first taste the wasabi. At that time, some customers say, ‘Delicious,’ and others say, ‘This is the best among those I have ever eaten,’” Sato said.

To meet the expectations of such customers, Sato has adhered to a method of grating wasabi after receiving an order.

“Wasabi produces a hot flavor and an aroma for the first time only after it is exposed to air. From that moment, however, the hot flavor and aroma begin to be lost,” he said.

The aroma spreads quickly when Sato slowly grates it with a “samekawa-oroshi,” or a grater covered with sharkskin. Customers react immediately, saying, “It has a good aroma.”

Such a reaction is also a pleasure Sato feels when he makes sushi.


Sato entered the industry when he was 19, aiming to become a sushi chef.

“Until then, I was not good at tasting wasabi at all,” Sato said. While working as a trainee, he was gradually attracted by wasabi.

“If I eat sushi without wasabi, I cannot be satisfied with it. I am bored with it even if I eat it. But if I experience the wasabi’s pungent fresh taste, the sushi becomes a completely different one,” Sato said.

According to Sato, what is important is adjusting the quantity of wasabi. If it is too much, it destroys the flavor of the ingredients. If it is too little, it cannot satisfy customers.

“When the portion of wasabi balances with the ingredients, sushi becomes extremely delicious,” Sato said.

It is a chef’s skills to best grasp the quantity needed, depending on the ingredients. Wasabi becomes less effective with items with a lot of fat, such as “otoro” (extremely fatty tuna), and those with a strong flavor, including “anago” (whitespotted conger). Sato slightly increases the quantity of wasabi for those ingredients. On the other hand, he decreases the volume for ingredients with a plain taste, such as “hirame” (bastard halibut) and “ika” (squid), as wasabi becomes more effective.

“Wasabi also plays a role in preventing the ingredients from slipping from the rice,” said Sato.

Ingredients that contain a lot of water and are solid, such as “kazunoko” (herring roe) and “awabi” (abalone), do not easily slide off if wasabi is used. As a result, the ingredients fit better with rice. They do even more so if the wasabi has adhesiveness.

As the restaurant is located in Akasaka, it has many foreign customers.

“Regardless of whether they are from Asia, Europe or the United States, foreigners like wasabi very much. Most of them ask us to serve wasabi in different plates,” Sato said.

Like “gari” (pickled ginger), wasabi is offered to customers free of charge. In Sato’s restaurant, however, it is one of the most expensive items when he buys it.

“In their early period, the prices of wasabi are the second highest following ‘shinko’ (young konoshiro gizzard shad). But I don’t care because it is necessary,” Sato said.

Sato always puts wasabi in a case containing ice and displays it in a location that can be seen by customers. The wasabi is also a big appeal of the restaurant.


The power of nature, such as abundant spring water, is indispensable for wasabi cultivated by Tashiro. But it is also receiving benefits from biotechnology.

It is not easy to grow wasabi to a level that makes it commercially valuable. But it is also difficult to propagate them. Even if farmers raise them from seeds or grow them by division, they cannot stably produce good-quality wasabi partly because the wasabi easily contracts diseases.

Because of that, farmers depend on cloned seedlings. They provide good-quality wasabi to Miyoshi Agri-tech Co., a seed and seedling company in Yamanashi Prefecture, to reproduce same-quality seedlings in large quantities. Like Tashiro, about 100 farmers in major wasabi-producing areas of Shizuoka and Nagano prefectures are asking the company to produce cloned seedlings.