There are several ways to shape sushi rice, and when you look at a finished piece of nigiri from the side, you may notice distinctive forms. These shapes not only influence appearance but can also affect how the sushi is perceived in taste, making them a surprisingly important element.
The most common style is the rice-bale shape (Kometawaragata). A rice bale, traditionally made of straw to store and transport rice, has a cylindrical form, and the sushi rice resembles this when viewed from the side. The bottom that rests on the plate is relatively flat, while the surface in contact with the topping has a gentle curve. This creates a natural harmony with the fish, especially with thinly sliced or oily toppings, making it a versatile and widely used shape.
Another, less common form is the boat-bottom shape (Funazokogata). Seen from the side, it looks like an inverted trapezoid, with the top wider than the base. Because the contact surface between rice and topping spreads out like a fan, it gives the topping firmness and presence. This makes it especially suitable for larger cuts of fish, allowing them to sit beautifully without losing their shape.
The process of forming nigiri is essentially the same for both. Whether it becomes rice-bale shaped or boat-bottom shaped depends on how the chef applies pressure with the fingers. Even pressure produces the rice-bale form, while adding more strength to the bottom creates the boat-bottom form.
There is no inherent superiority between the two. The difference lies simply in shape, not in the skill level of the chef. Understanding these subtle variations can add another layer of appreciation to enjoying sushi.
Many sushi chefs used the Jigamigata technique. The name comes from its resemblance to the paper used for folding fans when viewed from the side. Jigamigata is considered well-suited for nigiri with larger toppings. This may be because in the past, shari often weighed 15g or more, paired with larger pieces of sushi toppings. Nigiri styles can be divided into endless detail, so we’ll stop here.
It is worth noting that, in the culture of Edomae-style sushi, harmony with taste has traditionally been valued more than visual form. The focus has been on the integration of topping and rice and on how the nigiri dissolves in the mouth, rather than on perfect geometric shapes. Consequently, chefs’ training and cookbooks emphasize techniques to enhance flavor rather than the precise shape of the finished sushi. This is also why literature often discusses how to form sushi but rarely describes the final shape in detail.
Fish bearing the name “mutsu” signify that they are rich in fat.
In Japanese, aka means “red,” shiro means “white,” kuro means “black,” and gin means “silver.” Accordingly, names such as Akamutsu, Shiromutsu, Kuromutsu, and Ginmutsu can be understood as combinations of color terms with the fish name Mutsu.
Before examining each fish individually, it is useful to consider the meaning of the term Mutsu itself.
In certain dialects of the Shikoku and Chugoku regions, the expressions mutukoi or mutukkoi describe food that is “rich,” “heavy,” or “greasy,” as opposed to light and refreshing. This descriptive term, which emphasizes richness in fat, is thought to have evolved into the fish name Mutsu. In other words, the word Mutsu in fish names signifies “a fish rich in fat.” This designation was then combined with visible characteristics, such as coloration, to yield names like Akamutsu and Kuromutsu.
With this background in mind, let us now examine the four types of Mutsu, along with some related species.
Akamutsu (Common Name: Nodoguro)
The official name is Akamutsu, though it is more widely recognized by the common name Nodoguro (“black throat”), referring to the distinctive dark coloration at the back of its throat. Taxonomically, it belongs to the family Acropomatidae and is not closely related to the Kuromutsu of the family Scombropidae, discussed later.
Akamutsu is distributed primarily in western Japan and southward, as well as along the Sea of Japan coast. Kuromutsu, by contrast, inhabits the Pacific Ocean south of Iwate Prefecture and the Izu Islands. Compared to Kuromutsu, Akamutsu tends to live in slightly shallower waters.
Shiromutsu is a colloquial name; its official designation is Oomehata. Like Akamutsu, it does not belong to the family Scombropidae. It came to be called Shiromutsu because its flesh is whitish and rich in fat. Its formal name, Oomehata (“big-eyed grouper”), reflects its strikingly large eyes and a mistaken assumption of close relation to the grouper family.
In the Kanto region, the name Shiromutsu is more commonly used, though it is also sometimes referred to as Ginmutsu, leading to confusion. While it resembles Akamutsu in appearance, it can be distinguished by its very large eyes and a triangular anal fin.
Kuromutsu
The catch volume of Kuromutsu is quite limited, making it rare in ordinary household cuisine. Like Akamutsu, it has exceptional fat content and is considered among the most flavorful of fish. Due to both its rarity and its taste, it commands premium prices, sometimes surpassing even renowned high-end species such as Kue or Akamutsu.
Ginmutsu is the former Japanese market name for the Majeranainame (Common name is Patagonian toothfish), a large deep-sea species inhabiting waters around the Antarctic. A white-fleshed fish with a high fat content, it was once distributed in Japan as “Ginmutsu.” However, because it is taxonomically unrelated to Akamutsu and Kuromutsu, the use of this name was prohibited after the 2003 revision of the JAS Law, in order to prevent consumer confusion. Today, it is typically marketed in Japan under the name Mero.
Baramutsu and Aburasokomutsu (Related Species)
As a brief digression, Baramutsu and Aburasokomutsu are also fish whose names contain mutsu. Baramutsu is a deep-sea species in the family Gempylidae, characterized by an extremely high lipid content. Its flesh contains large amounts of wax esters, a type of indigestible oil, which can cause stomach pain and diarrhea in humans. For this reason, distribution of Baramutsu is prohibited in Japan.
Nevertheless, it is sold in the United States and is sometimes used deceptively as a substitute for other fish, although it is said to have an exquisite taste. In any case, members of the blackfin scabbardfish family, including Aburasokomutsu and Baramutsu, must be approached with caution due to their potential adverse health effects when consumed.
Mutsu (Standard Japanese Name)
The standard Japanese name Mutsu refers to a fish of the family Scombropidae. It closely resembles the Kuromutsu and is similarly prized for its rich, fatty flavor. This deep-sea fish is landed across Japan, from Hokkaido to Kyushu, and has long been regarded as a premium fish, especially in the Kanto region, where it is traditionally used in simmered dishes.
Because of their similar body shape and coloration, Mutsu and Kuromutsu are often not clearly distinguished and both may be sold as Kuromutsu. In the marketplace, however, they differ in price: Kuromutsu typically sells for more than twice the price of Mutsu, making cost an effective indicator of distinction.
Availability in Sushi Restaurants
In Tokyo sushi restaurants, the varieties most commonly offered are Akamutsu, Mutsu, and Kuromutsu. Since Mutsu and Kuromutsu are easily confused, many establishments label them uniformly as Kuromutsu. All of these are regarded as luxury fish, served only in select high-end sushi restaurants.
In my view, these toppings reach their full potential only when paired with shari seasoned with rich red vinegar and served with precise temperature control. Many sushi restaurants use lighter rice vinegar, which does not always harmonize with the oiliness of these fish. In some cases, it may even be necessary to prepare two different kinds of rice. Furthermore, in Tokyo, a single piece of such nigiri typically costs upwards of US$20.
The appearance of Kinmedai yakishimozukuri. Only the skin is seared.
In Japanese cuisine, it is common for the same cooking method to have different names depending on the season or context, which often leads to confusion. A good example of this is the distinction between yushimo and yakishimo. While they are similar, they are not identical, and understanding the difference is important.
The word shimo (霜) literally means “frost.” In cooking, shimofuri refers to a preliminary treatment in which food is briefly exposed to heat—by pouring boiling water over it, dipping it in hot water, or lightly searing it—so that the surface turns white, resembling frost. It is suitable for fish with beautiful skin or fish that are delicious when eaten with the skin on.
It also refers to the preparation step, similar to kawasimo or yushimo, where the fish is briefly dipped in hot water to remove scales and bloodline before preparing Arani (粗煮) or kabutoyaki (兜煮).
Shimofuri technique removes odors, sliminess, and excess fat while sealing the ingredient’s umami. It also firms the flesh and adds elasticity.
Yushimo (湯霜) comes from yu (hot water) and shimo (frost). It is a type of shimofuri in which the surface of fish or meat is treated with boiling water, either by dipping it quickly into hot water or by pouring hot water over it. The food is then immediately cooled in ice water and the moisture is removed before further preparation. This method is also known as yubiki (湯引き).
When used for sashimi, it is called yushimozukuri (湯霜造り). In this preparation, hot water is poured over the skin side of a fish fillet to soften the skin, after which the fish is chilled, the moisture is removed, and it is sliced. The result is an elegant appearance, with curled skin that enhances both flavor and presentation.
The term yushimozukuri refers not only to the cooking technique itself but also to the sashimi dish prepared using that method.
Yakishimo (焼霜), on the other hand, comes from yaki (to grill) and shimo (frost). This method involves lightly searing the surface of fish or meat until it develops a touch of browning, then cooled in cold water. Like yushimo, it removes excess fat and odor, but it also imparts a subtle roasted aroma. When used for sashimi, it is called yakishimozukuri (焼霜造り). This preparation is widely applied to fish such as red seabream, chicken grunt, barracuda, largehead hairtail, blackthroat seaperch, daggertooth pike conger, yellowtail, Spanish mackerel, bonito, and mackerel.
Depending on the style, the fish may be seared while still in fillet form (saku), or after being cut into sashimi slices. Just like yushimozukuri, the term yakishimozukuri refers both to the cooking method itself and to the sashimi dish created through that method.
Additionally, kawashimozukuri (皮霜造り) refers to sashimi in which the skin has been blanched in boiling water or over an open flame. This technique is also called matsukawazukuri (松皮造り) because, when applied to fish such as sea bream, it creates a pattern that resembles pine bark (matsukawa means pine bark). It enhances the umami of the skin while eliminating any fishy odor. It has the same meaning as Shimofuri and Yushimo.
In short, both yushimo and yakishimo are forms of shimofuri. Yushimo uses boiling water, while yakishimo uses direct heat from searing. Though their purpose is similar, each creates a distinct flavor, texture, and visual appeal, showcasing the ingredient in a uniquely Japanese way.
Grilling is more commonly done with meat than with sushi toppings.
Both Aburi and Tataki are Japanese cooking techniques that involve exposing food to high heat, but they differ in both purpose and process.
Aburi means “to sear,” and refers to lightly grilling the surface of food while leaving the inside raw.
In sushi, aburi is often applied to fatty cuts like salmon or tuna, where the flame enhances aroma, melts fat, and creates a contrast between the charred surface and the fresh interior. Some chefs use handheld gas burners, though Edomae-style masters often disapprove because of the faint odor left by the gas. For them, aburi is not about making the fish richer, but about controlling fat so the sushi remains balanced.
Other methods such as charcoal grilling, ovens, or iron plates can also be used, producing different aromas and textures. Aburi also appears in vegetables—like peppers or eggplants whose skins are charred and peeled—and in desserts such as crème brûlée or baked custard pudding, where caramelized surfaces are essential.
Tataki, in contrast, is more polysemous. In its seared form, tataki refers to quickly grilling the surface of fish or meat, then cooling it and slicing it.
Unlike aburi, tataki is always finished with seasonings: the slices are eaten with condiments such as soy sauce, ginger, garlic, or other pungent garnishes. This seasoning process is essential to the identity of tataki. The best-known example is katsuo no tataki from Kochi, where bonito is straw-seared, chilled in ice water, and served with generous amounts of aromatic condiments.
The term tataki also extends to finely chopping fish into a mince or even a paste, and to vegetables like cucumber or burdock root that are pounded to soften their texture, but in comparison with aburi, it is the seared and seasoned preparation that is most relevant.
Thus, while both techniques highlight the interplay of cooked and raw, aburi serves primarily as an aromatic finish that enhances natural flavor, whereas tataki is a preparation that combines searing with deliberate seasoning. This requirement of seasoning after searing marks a fundamental difference between the two.
When most people think of wasabi, they picture a bright green paste with a strong, nose-tingling heat. In reality, what is served in most sushi restaurants around the world—including in the U.S., Europe, Asia, and China—is usually imitation wasabi.
This is not because restaurants want to mislead customers, but because real wasabi is incredibly difficult to grow and very expensive. The Wasabia japonica plant needs pure spring water, cool temperatures, and several years of careful cultivation, which makes large-scale production nearly impossible. As a result, genuine wasabi is rare even in Japan, and much harder to find abroad.
Imitation wasabi is a food product primarily made from horseradish. It contains added coloring, flavoring, and thickening agents that give it the appearance and taste of real wasabi.
Imitation wasabi, made from horseradish, mustard, and green coloring, became the practical solution. It is affordable, easy to store, and widely available, which has allowed sushi culture to spread and become popular worldwide. Without this substitute, sushi culture might not have grown as quickly outside Japan.
Even in Japan, most wasabi served at conveyor-belt sushi chains or sold in supermarkets is not 100% hon-wasabi (hon means real). There are powdered forms that must be mixed with water, and smooth pastes packaged in tubes. Their compositions vary: some include a small amount of domestically grown wasabi rhizome, others add mustard powder for extra sharpness, and many rely primarily on horseradish. In other words, “imitation wasabi” in Japan exists on a spectrum—from blends with real wasabi to products made almost entirely from substitutes.
By contrast, at high-end sushi restaurants and traditional ryotei in Japan, chefs freshly grate real wasabi rhizomes on sharkskin graters and serve it directly with sushi. These chefs deliberately choose authentic wasabi because it brings out the natural character of the fish and rice. Its fleeting heat, subtle sweetness, and refreshing aroma work in harmony with the sushi rather than overpowering it. In other words, real wasabi is not just a condiment—it is an essential element that allows the true flavor of the ingredients to shine.
In recent years, a few farms in the United States—in places like Oregon, North Carolina, and California—as well as in Europe, China, and other parts of Asia have begun cultivating real wasabi. However, the same challenges remain: it cannot be mass-produced, so supply is very limited.
So while most people around the world—and even many in Japan—have only encountered imitation wasabi, it exists for very practical reasons. And when diners finally taste freshly grated real wasabi, they often discover a surprisingly delicate, even slightly sweet flavor unlike anything they expected.
For travelers visiting Japan, tasting real wasabi at a sushi restaurant or ryotei is a unique culinary experience. It is an opportunity to appreciate the subtlety and harmony of authentic Japanese cuisine—something that cannot be fully replicated elsewhere.
The main ingredients of soy sauce are soybeans, wheat, and salt.
The Deliciousness of Nigiri Sushi and the Role of Soy Sauce
The appeal of nigiri sushi lies in the balance between the vinegared rice
’s gentle acidity and the seafood’s natural umami.Soy sauce elevates this harmony, acting like a quiet but essential partner in the background—a supporting role without which sushi would feel incomplete.
So-called Kansai-style sushi, such as oshizushi, bozushi, and hakozushi, which developed from preserved foods, involves seasoning not only the vinegared rice but also the sushi toppings. Therefore, it can be eaten without soy sauce. However, Edomae sushi uses fresh ingredients and values the inherent flavor of those ingredients. This necessitated a soy sauce that wouldn’t compromise the natural taste of the ingredients but rather enhance it.
Soy sauce contributes more than taste. It also helps neutralize the fishy odor that vinegar alone cannot remove. For instance, in hikarimono like kohada, saba, and aji, even a light brush of soy sauce softens the smell and polishes the flavor.
Beyond flavor and aroma, soy sauce also plays a role in preservation. Just as vinegar and salt protect sushi from spoilage, soy sauce has long been recognized for its bacteriostatic properties. In this way, it supported the development of Japanese cuisine, which relies on raw ingredients even in Japan’s humid climate.
Whether through its color, taste, fragrance, or hygienic qualities, soy sauce is woven into the very foundation of Japanese culinary culture.
Traditional Soy Sauce in Edomae Sushi
Edomae sushi originally used seafood caught in Tokyo Bay, but from the Edo period onward, fish such as tuna were also brought in from distant waters. These were often marinated in soy sauce in a technique called zuke. The name itself comes from this marinade, and to this day, sushi shops that uphold Edomae traditions still serve maguro zuke. Thanks to modern freezing and storage methods, fresh tuna is available year-round, so zuke is no longer a necessity—but its deep, mellow flavor endures.
In the past, soy sauce was rougher and less refined than today. To suit their needs, sushi chefs would cook and season it, creating nikiri shoyu (“simmered soy sauce”). This is typically made by gently simmering soy sauce with 10–20% mirin, sometimes with sake, bonito stock, or water. After about 30 minutes, when bubbles form, the heat is turned off. The word nikiri—literally “simmered to completion”—is said to come from this step.
Although improvements in modern soy sauce mean some shops no longer use nikiri, many traditional Edomae sushi restaurants still brush it onto their nigiri, just as they continue the practice of zuke.
Among simmered toppings (nimono) like anago, shako, and hamaguri, another essential sauce is tsume (or nitsume). Made by reducing the simmering liquid of anago or hamaguri with soy sauce, mirin, and sugar until it becomes a rich glaze—about one-tenth its original volume—tsume has been perfected in each restaurant’s own style.
Traditionally, tsume is prepared when high-quality anago arrives. The head and bones are simmered to create a flavorful broth, which is strained and then combined with soy sauce, mirin, and sugar. It is slowly reduced over half a day into a glossy sauce. The choice of soy sauce here is critical, and many sushi chefs say that the depth of a restaurant’s tsume reflects its true character.
Conclusion
In sushi, soy sauce is far more than a condiment. It balances flavors, refines aromas, preserves freshness, and embodies tradition. The delicate ways in which it is used—through zuke, nikiri, or tsume—are a testament to the craft of Edomae sushi and remain central to the essence of sushi culture today.
The “aka” in aka shari means “red” in Japanese, while “shari” refers to the vinegared rice used in sushi. Literally, it means “red vinegared rice,” but it doesn’t actually refer to bright red rice; instead, it denotes vinegared rice with a slightly brownish hue.
Why is it called “red”?
Typical vinegared rice is made by mixing cooked white rice with rice vinegar or grain vinegar. These vinegars are clear or pale yellow and don’t significantly change the rice’s color. As a result, the general understanding worldwide is that vinegared rice is white. Occasionally, artificially colored vinegared rice—such as blue or purple varieties—can also be seen.
By contrast, aka shari is made with red vinegar or black vinegar. These are dark brown liquids, and when mixed with rice, they produce vinegared rice with a light brown tint. Red vinegar was traditionally used in Edomae sushi, which originated in the Edo period, and this practice gave rise to the term “aka shari.” Its opposite is “gin shari.” While “gin” means silver, in this context it refers to pure white sushi rice.
However, making sushi rice exclusively with red or black vinegar results in a color that is too dark and an aroma that is overpowering, leading to an unbalanced taste. Although these vinegars are rich in umami components like amino acids, using them alone disrupts the overall harmony and can be polarizing in flavor. For this reason, sushi chefs commonly blend them with rice vinegar or grain vinegar. In fact, vinegar producers even sell blended vinegars specifically designed for vinegared rice.
Just as with other fermented foods, not everyone appreciates the flavor of aka shari made with red or black vinegar. While some chefs use it to emphasize the traditional prestige of Edomae sushi, it doesn’t always suit sushi that relies on a refreshing acidity.
Summary
Aka shari refers to sushi rice made with red vinegar, a hallmark of Edomae sushi. Its distinctive flavor and color add depth, but it is challenging to handle and not to everyone’s taste. How red vinegar is blended with other vinegars, and how the final rice harmonizes with sushi as a whole—this is where the craftsmanship and philosophy of the sushi chef truly shine.
Both sabazushi and battera are types of oshizushi made with mackerel. Oshizushi is made by layering vinegared rice with vinegared mackerel and shiro-ita konbu, then pressing the mixture into a wooden mold. Mackerel has been abundant in Japan since ancient times, which led to the development of this dish as a practical preserved food.
There are clear differences between Sabazushi and Battera, so let us explain them.
The appearance of sabazushi
Sabazushi is said to have originated in the Edo period. Mackerel is salted and transported from its place of origin in Wakasa to Kyoto, where it arrives after 2 to 3 days, by which time the seasoning is just right. This salted mackerel is used to make Sabazushi. Even today, with the development of refrigeration technology, it remains popular with many people and is also a local dish of Kyoto. There are also long-established sushi restaurants that have been in business for generations. Additionally, Sabazushi can be found in other regions such as Hyogo, Hiroshima, and Wakayama, which have adopted the dish from Kyoto.
Sabazushi is prepared using a unique method. First, the air is removed from the vinegared rice to extend its shelf life. Then, the vinegar-marinated mackerel is formed into sticks with a cloth or bamboo mat. Finally, shiroita konbu or rausu konbu is placed on top to prevent the mackerel from drying out. Only half of the mackerel is used so that the thickness of the flesh is evident. The cross-section is rounded, which is why it is also called bozushi (bo means “stick”).
The appearance of battera
Next, Battera is a type of Oshizushi made by placing thinly sliced mackerel marinated in vinegar and shiroita konbu simmered in sweet vinegar on top of vinegared rice. It is typically shaped using a square mold. The mackerel is cut with a knife to minimize waste, resulting in an almost uniform thickness.
Battera is said to have been invented in 1894 by Tsunekichi Naka, the founder of Sushi Tsune, a sushi restaurant in Osaka. At the time, Sushi Tsune was selling Oshizushi made with Konishiro (Gizzard Shad), which was commonly caught in Osaka Bay. Due to its popularity, the traditional method using a cloth became insufficient for production, so a wooden, boat-shaped mold was used instead.
Customers reportedly referred to the mold as “bateira,” a Portuguese word meaning “boat,” which evolved into “battella.” Over time, this name further transformed into “Battera.” As the price of Konishiro (Gizzard Shad) rose, mackerel was adopted as an alternative, and due to its ease of shaping, square molds became the standard.
In summary,
Sabazushi: Use a bamboo mat to shape the fish into a round form, using thick slices of mackerel left whole. The cross-section has a rounded shape.
Battera: Shaped into a square using a wooden mold, thinly sliced mackerel is arranged evenly. The cross-section is square.
Sabazushi is a traditional regional sushi centered around Kyoto, while Battera is a type of sushi that became popular among the general public in Osaka.
This is what most people think of when they hear the word chirashizushi.
Recently, I came across an image on social media of Barachirashizushi made by an American sushi chef. I was surprised to see that Barachirashizushi, a dish traditionally made only by a few sushi restaurants that uphold the Edomae-style, had been created by a sushi chef outside Japan. However, it was labeled as Chirashizushi, which I found disappointing, so I will explain the difference.
The term “chirashizushi” (or “chirashi sushi”) originates from the act of scattering various ingredients over or within vinegared rice and is sometimes referred to simply as “chirashi.” Generally, “Gomokuzushi” refers to vinegared rice mixed with ingredients, while “chirashizushi” refers to vinegared rice topped with arranged ingredients. However, these terms are not strictly distinguished. The names may vary depending on the region (e.g., Kanto or Kansai) and generation.
First, let’s explore the origin of chirashizushi. The term “barazushi” appears here, but it is different from barachirashizushi.
Barazushi, a type of sushi from Okayama, is said to date back to the early Edo period. At that time, the feudal lord of Okayama Domain, Ikeda Mitsumasa (1609–1682), promoted frugality and simplicity. He issued the “One Soup, One Side Dish Edict,” which restricted side dishes to one item other than soup.
They finely chopped ingredients such as simmered shiitake mushrooms, kanpyo (dried gourd strips), and carrots and secretly mixed them into the rice. According to one story, sushi ingredients were placed at the bottom of a box and covered with seasoned rice to disguise them as a simple meal. The box was then flipped over just before serving.
As “Barazushi” spread throughout Japan, a style of scattering the ingredients on top of the vinegared rice rather than mixing them in was developed, and this became known as “Chirashizushi.”
Now, let’s look at the difference between chirashizushi and barachirashizushi, focusing on the names used in sushi restaurants in Tokyo.
The appearance of Chirashizushi
In Tokyo sushi, specifically Edomae sushi, Chirasushizushi refers to a dish where sushi toppings used for Nigiri sushi are arranged on top of vinegared rice (also known as Namachirashi, Fukiyosechirashi, or Edomaechirashi). However, in regions outside the Tokyo area, Chirashizushi generally refers to a dish where seasoned ingredients are mixed into vinegared rice and decorated with shredded omelette and seaweed (also known as Gomokuzushi or Barazsuhi). This is just my personal opinion, but I think that even in Tokyo, the latter is called chirashizushi.
Dishes made with plain white rice rather than vinegared rice are generally called seafood bowls. Sushi restaurants do not serve bowls of plain white rice (they cannot), but some restaurants call dishes made with vinegared rice seafood bowls. In my personal opinion, most seafood bowls served outside of sushi restaurants are made with plain white rice.
The appearance of Barachirashizushi
Additionally, a dish with randomly arranged sushi toppings on vinegared rice is called “barachirashizushi.” Some traditional sushi restaurants in Tokyo offer two types: chirashizushi, which is primarily served in-store, and barachirashizushi, which excludes toppings that are not suitable for takeout and can be taken home.
Incidentally, chirashizushi made with sushi ingredients is not typically prepared in Kanto-style households. More precisely, it may include decorative toppings such as ikura (salmon roe), tobiko (flying fish roe), and steamed shrimp; however, the standard ingredients are dried shiitake mushrooms, lotus root, carrots, snow peas, and shredded omelet.
Other names for ao-negi include ha-negi, sho-negi, and bannō-negi.
We think foreigners may be unable to tell the difference between Japanese green onions just by looking at them. There are two main types, but even though they are the same onion, they have different names, which can be confusing. In the Kanto region and northern Japan, shiro-negi (Japanese leeks) are commonly eaten, while in western Japan, ao-negi (green onions) are the mainstream variety. Green onions used as a condiment in udon and soba noodles are also Japanese leeks in the east and green onions in the west.
Other names for Naga-negi include Shiro-nrgi and Nebuka-negi.
Onions with more white parts are called “Nebuka-negi (根深ネギ),” while those with more green parts are called “Ha-negi (葉ネギ).” In Eastern Japan, the term “negi” simply refers to Nebuka-negi (also called Naga-negi or Shiro-negi), which is grown by mounding soil around the plant as it grows to protect it from direct sunlight, resulting in a strong flavor and thick stems. Other types are distinguished by specific names such as “Wakegi,” “Asatsuki,” “Bannō-negi (also called sho-negi),” and “Kujo-negi.” In western Japan, the thin Ha-negi grown in the sun is called “Ao-negi,” and Nebuka-negi is sometimes referred to as “Shiro-negi” or “Nebuka.”
In summary, the word negi in Japanese cuisine is a broad term that can refer to several varieties: Ao-negi (青ネギ), common in western Japan; Naga-negi (長ネギ), more popular in eastern Japan; and their subtypes such as Bannō-negi (万能ネギ), an improved cultivar of Ao-negi, and Kujo-negi (九条ネギ), a Kyoto specialty. These variations can be confusing to foreigners, but they reflect how regional food culture has shaped the way green onions are used in Japanese cooking.
Onions Commonly Used in Sushi Restaurants
In Japanese sushi restaurants, several types of onions play important supporting roles in flavor and presentation. The most common are Bannō-negi (万能ネギ), a versatile fine green onion; Ao-negi (青ネギ), the standard leaf onion; Naga-negi (長ネギ), a long Welsh onion often used as Shiraga-negi; and Me-negi (芽ネギ), the tender young sprout onion. Each type has its own distinct characteristics and culinary uses.
Bannō-negi, often translated as “fine green onion,” is actually an improved cultivar of the broader Ao-negi group. Compared to standard Aoba-negi, it is thinner, softer, and milder, making it especially suitable as a garnish for sushi or sashimi.
By contrast, Naga-negi has a thick white stalk. In sushi, it is often shredded into fine strips called Shiraga-negi (白髪ネギ), which are placed on top of fatty fish to balance richness with a refreshing sharpness. By the way, Shiraga (meaning “white hair”)-negi refers to the white part of Naga-negi, sliced thinly like white hair.
Another variation is Me-negi, which are delicate and visually appealing. They provide a crisp texture and a subtle, grassy fragrance that complements lighter sushi toppings.
Together, these different forms of onions demonstrate how sushi chefs carefully choose the right variety to balance flavor, texture, and presentation.
Sashimi is a standard menu item at whale specialty restaurants.
It has been six years since Japan withdrew from the International Whaling Commission (IWC) and resumed commercial whaling. Many consumers had hoped that whale meat would become cheaper and appear on dinner tables. This is because whale meat is a nutritious and versatile ingredient that can be used in a variety of dishes. However, the amount of whale meat available in circulation has decreased compared to the era of research whaling. What exactly were the Japanese government and the whaling industry trying to protect?
On the other hand, the three countries strongly pushing for a “whale hunting ban” in Japan are the United States, Australia, and New Zealand. Why is Japan not allowed to engage in commercial whaling when Iceland and Norway are permitted to do so? Such inconsistencies also exist.
In fact, very few Japanese people actually want to eat whale meat. According to a survey by Greenpeace, 95% of Japanese people do not particularly want to eat whale meat. It is said that the average annual consumption of whale meat per person in Japan is now 40 grams. It was quite a challenge to find images of whale sushi in our saved files.
In other words, whales may now be used as political and economic tools, transcending issues such as human food and the environment.
To put it bluntly, it may be the fault of a few members of parliament elected from constituencies with many whaling-related interests and hundreds of bureaucrats who do not want to lose their budgets.
This article is simply to show that whale sushi exists as part of Japanese food culture. Although rare today, whale occasionally appears as sushi neta (topping). So, what kinds of whale are actually used for sushi? Let’s take a closer look.
Minke whales in the northern hemisphere are about 8 meters long. Seen from above, their heads are pointed at the tip. There is a white patch on the upper center of the pectoral fins. The dorsal fin, about 30 cm high, is located toward the rear of the body and is often clearly sickle-shaped. The back is black, the sides are gray with a blurred pattern, and the lower jaw and abdomen are white.
It generally feeds on krill, small squid, and fish. It filters its food through bristle-like baleen plates, made of keratin. The Japanese name for the minke whale is higekujira, which means bearded whale.
Description: A relatively small baleen whale, measuring about 7–10 meters in length.
Use: The most commonly caught species in Japan’s commercial whaling, widely utilized for sushi toppings, sashimi, and bacon-style preparations.
Flavor: The red meat is tender with little odor, making it one of the more approachable types of whale meat.
Bryde’s Whale is a close relative of the Sei whale. It was named “Nitarikujira” (meaning “similar whale”) because it resembles the Sei whale. It grows to a maximum length of about 15 meters and is slightly smaller than the Sei whale.
Description: A medium-sized baleen whale, usually 12–15 meters long, larger than the minke whale.
Use: Its red meat is served as sushi or sashimi, while fatty cuts and tail meat are often cooked.
Flavor: The red meat has a richer taste with a pronounced umami and iron-like character.
3. Sei Whale (Balaenoptera borealis Lesson, 1828)
Sei whales are baleen whales belonging to the family Balaenopteridae. They migrate across the open ocean in schools of sardines, feeding on them, which is how they got their name.
Two subspecies are recognized: the northern hemisphere subspecies (B. b. borealis) and the southern hemisphere subspecies (B. b. schlegelii). They are distributed in the southern Indian Ocean, the North Atlantic and South Atlantic, and the North Pacific and South Pacific.
Its body is slender and spindle-shaped, with a sickle-shaped dorsal fin. The dorsal color is dark blue, the ventral color is light blue, and there are blurred patterns in between. The head is V-shaped, enabling it to swim at high speeds. The maximum body length is approximately 18 meters.
Description: A baleen whale that grows 12–18 meters long. In the past, it was more frequently caught, but today only limited numbers are harvested.
Use: The lean red meat is used for sushi or sashimi, while fattier portions are processed into bacon or fried dishes.
Flavor: The meat is tender and relatively mild, with a clean, elegant taste.
Sperm whales are distributed worldwide from the Arctic to the Antarctic, with the largest populations found in deep ocean waters. Male sperm whales grow to a length of 15 to 20 meters and weigh between 40 and 60 tons. Their body color is blackish gray, but it becomes whiter with age. In particular, the head tends to become whiter. The dorsal fin is mountain-shaped, with several ridges extending from the rear toward the tail fin. The surface of the body, except for the head, is rough and uneven.
Description: A toothed whale and one of the largest whale species, reaching 15–20 meters or more in length.
Use: Rarely used as sushi. Instead, its distinctive fatty tissue is made into “toothed whale bacon” or other processed foods.
Flavor: The fat has a unique aroma and a very rich, heavy taste.
Types of whale meat
Saezuri
Saezuri is very fatty, and the taste and texture differ between the root and tip of the tongue. It has a deep umami flavor and is used in simmered dishes and oden. It is one of the most popular delicacies of whale meat.
Onomi
The back section from the dorsal fin to the tail, with fat marbled like snowflakes (shimofuri). Considered the most delicious part of whale meat, it is also known as whale Otoro.
Unesu
The white, accordion-shaped part running vertically from the lower jaw to the navel is called Une, and the red inner part is called Sunoko. These two parts together form Unesu. It has a soft, gelatinous texture and is one of the most popular whale meat cuts, cherished for generations.
Bacon
Bacon is a processed food made by salting and smoking the part called Unesu.
Sudachi is small in size with an intense aroma and a sharp, refreshing acidity. In contrast, kabosu contains more juice and offers a milder sourness, giving it a soft flavor that enhances other ingredients without overpowering them. Sudachi is about the size of a golf ball, while kabosu is about the size of a tennis ball.
【Nutritional value of kabosu】
Vitamin C
Citric acid
Potassium
Pinene
Limonene
【Nutritional value of sudachi】
Sudachitin
Vitamin C
Citric acid
Potassium
Beta-carotene
Vitamin E
Calcium
Dietary fiber Polyphenols
At sushi restaurants, these characteristics are carefully utilized. Sudachi is often paired with delicate toppings such as white fish or shellfish, where just a drop can add a refreshing fragrance and highlight the clean flavors of the fish. It is particularly valued when the sushi chef wants the citrus aroma to leave a memorable impression or to give a lighter, fresher finish to the sushi.
Conversely, using sudachi repeatedly in an omakase course can mask the flavors of the sushi toppings.
Kabosu, on the other hand, is chosen when the balance of flavors is more important than fragrance alone. Its gentle acidity and abundant juice make it suitable for richer or fattier fish, grilled items, or simmered dishes, where it softens heaviness and provides an elegant aftertaste.
The appearance of Kikabosu
Aged kabosu (Kikabosu), with its mellow and rounded aroma, is sometimes used to enhance the sophistication of high-end sushi. For example, a light drizzle of kabosu over sushi made with the mild-flavored pen shell (Tairagi) elevates the shellfish to a higher level. Sudachi or young kabosu, however, are too pungent and would merely serve as a simple accent.
In short, sushi chefs distinguish between the two by using sudachi when they want to highlight aroma and freshness, and kabosu when they wish to bring harmony and subtlety to the flavor.
The freezer compartment of a household freezer typically operates at -18°C. However, in practice, due to factors such as how often the door is opened and closed, the temperature often only reaches around -12°C. While this is cold enough to freeze water, it does not freeze the core of the food, so it may appear frozen at first glance. Proteins, enzymes, and lipids remain unfrozen, causing the taste and texture of the food to deteriorate significantly within a few weeks.
On the other hand, ultra-low temperature freezing can freeze all the components of fish meat, suppressing protein decomposition and stopping lipid oxidation. This makes it possible to store food for up to six months. All living organisms begin to age and deteriorate after death, eventually leading to oxidation and decay. The temperature that can stop this process is the world of ultra-low temperature freezing at -42°C.
Inhibition of enzymatic protein degradation
Under normal conditions, proteins that have ceased activity at room temperature undergo enzymatic degradation. For example, the proteins in freshly caught fish are in a high-molecular-weight state. Through enzymatic degradation, they break down into lower-molecular-weight compounds, advancing the aging process. If this process progresses too far, decay occurs.
Additionally, fish have a high water content of 70%, making them age much faster than livestock meat. Therefore, the key is to quickly cool the fish to ultra-low temperatures after catching them and then thaw them while maintaining the aging process.
Inhibition of fat oxidation
What is commonly referred to as “freezer burn” occurs when the fat naturally present in food rises to the surface and oxidizes, causing the color to turn yellowish and the appearance and taste to deteriorate. To prevent this, it is essential to prevent the food from coming into contact with air. Furthermore, by storing it in an ultra-low temperature environment, the oxidation process itself can be almost completely halted.
Inhibition of microbial proliferation
Even at the -18°C environment of a household freezer, microbial proliferation can be largely suppressed. However, for complete inhibition of all types of microbial growth, ultra-low temperatures are ideal.
Real-world applications
Ultra-low temperature freezing is already widely used in the seafood industry. At Tokyo’s Toyosu Market, premium tuna is stored and transported at -60°C to preserve its deep red color, fatty texture, and fresh taste for overseas shipments. In Hokkaido, Pacific saury is frozen at -50°C immediately after being caught on specialized vessels, allowing them to be enjoyed months later with near-fresh quality. Some Japanese supermarket chains use -45°C freezing for salmon fillets, enabling them to offer sashimi-grade products all year round while minimizing quality loss.
In sushi restaurants, anago (saltwater eel) is often purchased in bulk when prices are stable, stored at ultra-low temperatures, and thawed to maintain quality and cost efficiency. Likewise, ikura (salmon roe) is typically prepared in autumn, its peak season, and frozen for year-round use, ensuring consistent flavor and texture regardless of the season.
The fact that a 10,000-year-old mammoth excavated from Siberian permafrost was still edible after being cooked is a testament to the capabilities of ultra-low temperatures.
At first glance, Ikura and Sujiko look quite similar — both are salmon or trout roe — but they differ in preparation, flavor, texture, and how they are eaten. Here’s a closer look at their differences.
What is Ikura?
The word ikura comes from Russian, meaning “fish roe” or “small grains.” In Russia, it can refer to various types of roe, including caviar and cod roe. In Japan, however, ikura generally refers to salmon or trout roe, and in the fishing industry, it often means only salmon roe.
Ikura is made from mature salmon roe that is removed from the egg sac, separated into individual eggs through a mesh, and then seasoned — typically with salt or soy sauce. The grains are large, bursting in the mouth with a satisfying “pop,” releasing rich, buttery flavor. Because of its beautiful appearance and texture, ikura is commonly used for sushi, rice bowls, and various appetizers.
What is Sujiko?
Sujiko is made from immature (Not just before laying eggs) salmon roe that is salted while still wrapped in the membrane of the ovary. The eggs remain connected like a string (suji: 筋 in Japanese), which is where the name comes from. Since the eggs are less mature, the grains are smaller than those of ikura, and the texture is more dense and creamy.
There are two main ways to season sujiko:
Traditional salting (塩漬け) – The roe is salted to draw out umami, then salted again to finish the process. Freshness is critical; roe processed immediately after the fish is caught will be less salty and have better texture, while roe processed later will taste saltier and lose some texture.
Soy sauce marinating (醤油漬け) – A modern method that uses soy sauce which does not darken the roe, preserving its bright red color.
Historically, sujiko was considered a very salty preserved food and was thought to pair poorly with vinegared rice, so it was rarely used in sushi. However, with the rise of low-salt and soy sauce–marinated sujiko, it has started to appear in sushi and other creative dishes.
Texture – Ikura: bursts in the mouth / Sujiko: creamy and dense
Use – Ikura: sushi, donburi, appetizers / Sujiko: rice topping, onigiri, and now occasionally sushi
Both ikura and sujiko are symbols of autumn in Japan. Knowing the differences will help you appreciate their unique qualities — and choose the perfect roe for your meal.
Koku is a comprehensive sensory experience derived from the combined stimuli of taste, aroma, and texture in food. It refers to a phenomenon characterized by the complexity of these stimuli, further enhanced by a sense of spatial expansion and lingering persistence.
Just as taste is defined by the five basic categories of sweetness, saltiness, bitterness, sourness, and umami, Professor Toshihide Nishimura of Kagawa Nutrition University explains that koku can also be described through three fundamental elements: complexity, mouthfulness, and lingeringness.
While these three terms are individually recognized internationally in relation to flavor, there is no direct English equivalent that fully captures the nuance of the Japanese concept of koku when these elements are combined.
The first element, complexity, can be objectively evaluated based on the diversity of chemical compounds present in a food. For instance, fermented foods like soy sauce and miso develop hundreds of additional compounds as they age—meaning a batch aged for two years will typically have much greater complexity than one aged for only one year. Similarly, foods that are cooked for extended periods, such as stews, tend to develop a more intricate flavor profile due to the formation of a wider range of substances, which enhances the sense of koku.
The second element, mouthfulness, is closely tied to retronasal aroma—the aroma that travels from the back of the throat into the nasal cavity during chewing and swallowing. Retronasal aroma plays a critical role in how we perceive flavor. This becomes particularly evident when we catch a cold: with nasal congestion impairing our sense of smell, foods suddenly seem flavorless. In fact, the olfactory system is considered more advanced than the gustatory system in distinguishing fine differences. For example, when chewing vinegared rice, the aromas of vinegar, kelp broth, and seaweed gradually rise through the back of the throat into the nasal passages. Aromatic molecules linger on the mucous membranes of the nasal cavity, allowing the brain to continue interpreting them as part of the overall taste experience.
The third element, lingeringness, is often enhanced by the presence of fat. Fat readily absorbs and retains aromatic compounds, allowing them to adhere to the mucous membranes of the tongue and nasal passages, thus prolonging the flavor experience. While we often describe fatty foods as “rich and flavorful,” it’s important to note that fat itself is tasteless and odorless. The perceived flavor comes from the wide range of compounds that dissolve into the fat during cooking, creating a complex and lasting impression.
However, not all taste and aroma compounds in food are present at concentrations high enough to be consciously perceived. Here, the concept of a threshold becomes crucial—the minimum concentration at which a compound can be detected by the senses. Many flavor and aroma molecules exist below this threshold. While they are not individually detectable, they interact synergistically with other components to subtly but significantly shape the overall flavor impression.
These undetectable compounds function like hidden flavors. Rather than asserting themselves directly, they enhance the definition of other flavors and contribute to a balanced and harmonious profile. In this sense, they can be considered koku-enhancing substances that strengthen the depth, complexity, and persistence of the taste experience.
For example, a small amount of yuzu peel added to miso soup, a pinch of salt concealed in a simmered dish, or the synergistic effect of glutamic acid and inosinic acid in kelp-based broth—all of these contribute not through obvious presence, but by shaping the overall flavor, expanding the taste on the palate, and enriching the lingering aftertaste we associate with koku.
Thus, koku is not simply a “rich flavor” but a nuanced sensory phenomenon created by the interplay of clearly perceptible and imperceptible flavor elements. It emerges from thoughtful ingredient selection, careful cooking techniques, controlled aging, and subtle enhancements such as “secret ingredients.” All these components work together to create a dish with true koku.
This is why koku is so difficult to translate directly into English. It is not just a taste, but a layered sensory experience with temporal and spatial dimensions, lying at the very heart of Japanese cuisine. Understanding koku provides valuable insight into the richness of Japanese culinary culture and the refined craftsmanship that brings its flavors to life.
