Edomaesushi | Sushiblog－Sushiuniversity

What is Kakushiaji?

In Japanese cuisine (Including Edomae sushi), subtlety is often the key to perfection. One such subtle yet powerful technique is kakushiaji, or “hidden flavoring”—an approach that may seem minor, but can make a significant difference in the final taste of a dish.

Kakushiaji refers to a technique where a single seasoning (For example, sugar, vinegar, soy sauce, salt, etc.) is added to a dish. The Kakushiaji contrasts with the finished dish’s flavor, and is added in an amount too small to notice when served. This produces a clear improvement in flavor.

Examples include adding a little salt to heighten sweetness, or adding a little vinegar to a simmered dish. Sometimes these combination of flavors can be quite surprising, like adding a touch of chocolate to a curry.

In its narrower sense, kakushiaji refers specifically to seasonings or spices that please the palate or the nose. However, in a broader interpretation, it encompasses all the nuanced techniques and invisible efforts that contribute to the deliciousness of a dish. This includes selecting quality ingredients, using seasonal produce, applying seasonings at the right time and in the right way, choosing appropriate tableware, and ensuring a beautiful presentation.

In essence, kakushiaji is not just about taste—it reflects the spirit of craftsmanship and attention to detail that defines Japanese cooking. It is the hidden touch that turns ordinary food into an extraordinary experience.

A list of Kakushiaji

soy sauce
miso
dashi
ketchup
Worcester sauce
mustard
sake
mayo
mirin
chocolate
coffee
cocoa powder
honey
spices (nutmeg, all spice, garam masala, cinnamon, cardamom, etc)
brown butter
chili oil
shio koji
amazake
yogurt
caramelized onions
sugar
cream cheese

What is Umami?

Umami describes the delicious taste of savory flavor essences. For many years, people held to the belief that humans can taste only four basic flavors (sweet, sour, salty, bitter) until a Japanese chemist named Kikunae Ikeda discovered a fifth flavor (glutamic acid) in the early 20th century.

The main umami ingredients are glutamic acid in seaweed, inosinic acid in dried bonito and meats, succinic acid in shellfish, guanylic acid in shiitake mushroom.

Many ingredients contain a wide variety of umami essences. In combination, they create a synergistic effect that produces an even more potent savory flavor.

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Revision date: July 9, 2025

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Is the handmade ginger in quality sushi restaurants free?

The ginger served in sushi restaurants is called “gari”. Some people eat it endlessly, thinking that it’s free no matter how much they eat.

However, at high-end or traditional sushi restaurants where artisanal gari is made in-house, it may be included in the bill. This is because crafting delicious, high-quality gari requires considerable time, skill, and labor, and the cost of fresh, domestic ingredients can be so high that serving it for free would result in a financial loss.

In contrast, the majority of sushi restaurants use commercially produced gari, which is mass-produced by large food processing companies, many of which have factories in China or Southeast Asia. These manufacturers typically soak large amounts of ginger in an industrial pickling solution containing salt, vinegar, acidulants, sodium saccharin, potassium sorbate, and sodium metabisulfite.
Although the quality of this mass-produced gari has improved in recent years, some versions have crushed and may be artificially colored with plum vinegar to enhance their appearance.

On the other hand, homemade gari, especially when made in Japan, is prepared with a more delicate and refined approach. It is typically seasoned with rice vinegar and salt, with sugar used sparingly to provide a gentle sweetness. The result is crisp, chewy, and flavorful, retaining the natural pale yellow color of fresh ginger without artificial coloring. During the early summer season, when young ginger (also known as shin-shoga) is harvested, the price of domestic ginger can soar to several thousand yen per kilogram. Due to its high water content, 1 kilogram of raw ginger yields only about 300 grams after squeezing.

Making high-quality, handcrafted gari is both cost-intensive and laborious, as sushi chefs often prepare a year’s supply in advance. Once made, it must be stored in a refrigerator dedicated exclusively to preserving the freshness and quality of the gari. When you consider the cost, effort, and culinary craftsmanship involved, it becomes clear that homemade gari is far more expensive and distinctive than its imported counterpart. In fact, serving authentic, house-made gari is one of the key elements that sets high-end sushi establishments apart from the rest. And even if you’re not charged for it, eating too much can dull your taste buds, affecting your appreciation of the sushi’s delicate flavors.

How to Make Gari (Pickled Ginger)

Slice fresh young ginger thinly.
Place the slices in boiling water.
Once the water returns to a boil, remove the ginger.
Drain the slices in a colander.
Spread the ginger out on a bamboo sieve (or similar) and press it firmly while still hot to remove excess moisture.
Soak the ginger in a seasoned vinegar mixture for half a day to a full day.

Vinegar Mixture (for 4kg of ginger):

3.8 liters of rice vinegar
1.5 kg of sugar
300 grams of salt

What is the difference between “鮨,” “鮓” and “寿司” (all ready “Sushi”).

As far as we know, there are three ways “sushi” is written on sushi restaurant curtains in Japanese kanji characters: 鮨, 鮓 and 寿司.

Do you know the difference? Most Japanese people don’t know the answer to this question.

This is because various spellings are used by sushi restaurants throughout Japan.

For example, in Hokkaido, “鮨” is used. Next, in Tohoku, Akita and Yamagata use “鮨,” Aomori, Iwate, and Fukushima use “すし,” and Miyagi uses “寿司.”

In Kanto, Gunma, Saitama, Tokyo, and Kanagawa use “鮨,” Ibaraki and Chiba use “すし,” and Tochigi uses “寿司.” The spellings vary by prefecture.

Incidentally, among the 42 prefectures (excluding Nara, Wakayama, Kochi, Saga, and Okinawa), the most common spelling is “鮨” with 20, followed by “すし” with 17, ‘寿司’ with 4, and “鮓” with 1.

Broadly, in the Kanto area 鮨 is generally used while 鮓 is more common in Kansai. 寿司 is used commonly everywhere in Japan.

On the other hand, of the three, only 鮨 and 鮓 are seen in ancient Chinese literature. 鮨 was seen as a dictionary entry as early as the 5th to 3rd centuries B.C., and it’s origin is described as combining “fish” and “shiokara” (briny flavor) resulting in the term 鮨.

On the other hand, in A.D. 1st to 2nd century dictionaries, “鮓” appeared, and is explained to depict “a storage container for fish.” Toward the end of the second century 鮓 was used for the term “narezushi”.

But around the third century, the briny meaning of 鮨 and the term “narezushi*” written as 鮓 started to be used interchangeably. That is how the words were imported to Japan.

In Japan, the character “鮓” was often used in literature from the end of the Heian era to the end of the Edo era. Eventually the use of “鮨” was revived during the Meiji era (for unknown reasons). It was a natural transition that Kanto came to use “鮨” and Kansai came to use “鮓”.

Incidentally, the kanji “寿司” was created from the phonetics. Its use for celebratory occasions became commonplace throughout Japan.

*”Narezushi (熟れ寿司)” is the primitive version of Japanese sushi. It means covering seafood with salt and then soaking in rice for a few years as a form of lactic acid fermentation, which brings out the acidity.

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Revision date: May 31, 2025

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Assessing Fish at the fish market!

One important task of sushi chefs is going to Tsukiji (Toyosu) every morning, looking at fish with their own eyes and assessing the quality. Having a good eye is important in order to get the highest quality possible, but this is cultivated by experience. They are also constantly obtaining information from the fishmongers at the market regarding what the best fish of the season and their localities. It’s almost a game as to whether they can get high-quality fish at the optimum price everyday. The skills of a sushi chef start with this assessment.

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Revision date: September 11, 2018

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Why do sushi chefs make the sushi in front of the customers?

A photo of sushi chef — It is enjoyable to see sushi chefs at work.

Everyone can relax and enjoy a meal at a familiar restaurant. However, when visiting a new restaurant for the first time, you may feel a little nervous and find it difficult to concentrate on the food. You may feel a sense of being out of your element.

The purpose of going to a sushi restaurant is to eat delicious sushi. There should be no disagreement about that. And many regular customers at sushi restaurants enjoy casual conversation with the sushi chefs. The topics range from sports like baseball and soccer to politics, economics, and the opposite sex. The more skilled the sushi chef, the more they can remember all the conversations in chronological order.

For travelers who don’t speak Japanese, it may be hard to understand, but sushi restaurants are the only places in the world where customers can have a direct conversation with the head chef.

When I mentioned this, someone argued that at teppanyaki restaurants, you can watch the chef’s performance while having a conversation. In our opinion, that’s the same as a street performer. The performance should take priority over conversation.

Sushi chefs look at all their customers and adjust the timing of serving food for each one. Of course, they also want customers to see their beautiful techniques, but there’s no special reason why they have to make sushi in front of customers.

So why do they make sushi in front of customers?

Generally, it plays an important role in enhancing the transparency in the cooking process and instilling trust in customers regarding hygiene management and quality maintenance. But that’s not all. Sushi chefs are expected to learn communication and create the right atmosphere on their own. Because sushi tastes better in a fun atmosphere than when eaten in silence.

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Revision date: May 19, 2025

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There are two ways to make anago nigiri sushi, “skin-up ” and “skin-down”.

A photo of anago nigiri sushi — The appearance of anago nigiri sushi

“Anago nigiri sushi” is a type of sushi where eel, simmered and cut into a fillet, is placed on top of vinegared rice and brushed with a sauce called “tsume.” The head and bones of the eel are simmered to create a broth, which is then seasoned and reduced to make the tsume.

When cooked, anago (conger eel) becomes very tender. On the flip side, this means it also falls apart easily. “Falling apart” refers to the dish becoming mushy and falling apart. The fish’s bones and flesh become mushy, resulting in an unappetizing appearance.

There are two solutions to prevent falling apart.
The first is to wait until the anago broth has cooled before removing the eel. This is the most effective method to prevent falling apart. As the eel cools, the gelatinous substance in the flesh solidifies, allowing it to be easily handled even when the anago broth has cooled.

The downside of this method is that the eel solidifies in a curled shape. When using it for nigiri sushi, it might be more convenient if the eel is stretched out. Additionally, since the eel hardens when cooled, forcing it flat while it’s hard can cause the flesh to crack.

The second method is to cook the eel in a bamboo basket and remove it while it is still hot.

That’s all you need to do to prepare the anago.

Next, we will describe the characteristics of anago itself. The naval (actually the anus) in the middle of the body serves as the border separating the head part (top) and tail part (bottom) of the eel. The fat and umami are distributed better on the top. People used to say that since the bottom moves more it is more tasty. This applies to fish in general.

Additionally, in sushi restaurants, it’s also often said, “the top should be served skin-up and the bottom should be served skin-down.” Please refer to the following for explanations of skin-up and skin-down.

As shown in this image, skin-up means that the skin side is on top and the meaty side is on the rice.

As shown in this image, skin-down means that the meaty side is facing up and the skin side is on the rice.

To tell the truth, anago easily melts apart when it is boiled and broth enters the part where it separates, so the appearance is not as appealing. In this case, it is better to make sushi using skin-up. But unless the crack is extremely obvious, whether to skin up or skin down is up to the sushi chef’s discretion. Skin-up can be cooked with tsume, and skin-down can be seasoned with salt and citrus juice to bring out the flavor.

For your reference.

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Revision date: May 30, 2025

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The migrating route of Inshore Pacific bluefin tuna and fishing place!

An illustration of Kuro maguro main prodution area — This is the migration route of Kuro maguro (bluefin tuna).

Tuna caught in the coastal regions of the Japan Sea is notable as the best bluefin tuna in January. Iki, a small island in Kyushu area is one of the famous ports for tuna.

In February and March, the tuna auction market becomes slack due to rough weather. Just a few tunas from Nachikatsuura where is also the famous port for tuna are on the market.

In March and April, tunas become thin because their eggs need many nutrients.

In May, large tuna is seldom seen in the Tsukiji Fish Market. Even if there is, its body is really thin. “Kinkaimono” which means a shore-fish is generally considered as high-class tuna, but in this season, imported tuna is useful instead.

It is said that Pacific Bluefin tunas spawn around Japanese waters between Taiwan and Okinawa in April and May. And then, they go up to fertile, north sea along the eastern coast of Japan.

In June, “Chubo” which is young and small tuna is taken hugely off the coast of the Sea of Japan. The school of Chubo begin moving northward in this season.

In July and August, tunas can be seen occasionally but their bodies are still thin. Instead, Boston Tuna which is caught in the Atlantic Ocean and nicknamed “Jumbo” is on the market. Its fresh is softer than “Kinkaimono” and it doesn’t have medium-fatty part which “Kinkaimono” has.

In September, Boston Tunas are at their best with plenty of fat on them. The best season of Boston Tuna is limited and ends in October. But fortunately, Japanese tunas come into season.

The school of tunas split up into two groups, the one takes Pacific Ocean route and another takes the Japan Sea route and both of them move northward along the Japanese Islands. Some of them reach the Tsugaru Strait where and the season of Tuna begins from September to next January. Oma town and Toi town is famous nationwide for its catch of tuna from the Tsugaru Strait. The flavor of tuna in September is still weak but it becomes stronger in October. In November, feed of tunas such as Pacific saury or Japanese common squid with plenty of fat increase and flavor of tuna also gets stronger. In December, the peak season comes around.

A catch of tuna falls off in January and it enters the final season. The temperature of sea water gets cold and feed of tuna, squids decrease and the fishing season in this area ends.

Tuna is matured to rest before it is used.

Once a bluefin tuna is caught, it arrives at Toyosu fish market within a day or two. However, that fish is not used as a sushi topping that day. No matter how good the tuna is, it starts very stiff and is not in a state where it should be eaten. The meat is hard and the white muscle lines are left in your mouth. The odor and acidic taste of the red meat is strong and the unique sweetness of the fish is nowhere to be found. After it has rested the muscles soften, bringing out the fat.

Then, when the sushi chef gets the tuna, he first separates the red, lean meat and the fatty toro portion, rewraps them separately, seals them in plastic, and puts them on ice. Next is waiting for the “young” meat, not yet suitable for eating, to mature. The number of days the fish will be rested depends on the size of the fish and the temperature. The smaller the cut and the warmer the temperature, the shorter the rest time. Generally the time is from 3-14 days.

The tuna wholesaler may also decide on the aging period independently. There is no right answer for this aging period, and it is decided based on the experience of the sushi chef.

This “young” fish not ready for consumption is a fresh, deep color but as it matures the color darkens, the fat is brought out and becomes a fleshy color. Proper care must be taken because if it’s rested for too long, the color changes too quickly.

As an aside, right after the tuna cutting show, it has not yet aged enough to be delicious. The color is light, and the production of umami ingredients such as inosinic acid is not sufficient. This is a show for advertising purposes.

Why do most sushi restaurants have 8 seats at the counter?

A photo of sushi restaurant — Most sushi restaurants have around 8 seats at the counter.

The main reason why many sushi restaurants operate with only around eight counter seats is to ensure the highest quality and to highlight the artistry of the chef.

In traditional sushi establishments, only the master chef prepares the nigiri sushi. Occasionally, there may be a senior apprentice who is allowed to make sushi as well, often someone on the verge of opening their own restaurant. In many cases, however, junior apprentices are not even permitted to handle knives. This is because the way a fish is cut can significantly alter its texture, which in turn affects the overall flavor and quality of the sushi. There is a noticeable difference between sushi prepared by the master and that made by an apprentice.

Equally important is the ability to read the subtle, often unspoken cues of the customer. Adjusting the pacing of the meal, the portion sizes, and the sequence and selection of ingredients is considered the true essence of counter-style sushi. For this reason, apprentices are first trained not in technique, but in observation. Learning to quietly watch the master’s rhythm, the timing of each course, and the space maintained between chef and guest forms the foundation of their training. Even without being explicitly taught, they absorb how to “read the customer” by emulating the conduct of seasoned chefs.

The true skill of a sushi chef lies not merely in serving sushi, but in the precise moment of “shaping” the shari and the topping. Sushi carefully prepared one piece at a time in front of your eyes is like a live performance. Everything from the amount of rice, the thickness of the fish, the pressure of the fingertips, and the movement of the hands is done in full view of the customer, allowing the skill of the chef to be conveyed directly. It feels like watching a work of art come to life before your eyes.

A sushi counter with just a few seats is not merely about space efficiency—it is a deliberate design meant to create an immersive “five-sense experience” that engages taste, sight, sound, smell, and even the feeling of time itself. The intimate and quietly focused atmosphere allows guests to step out of their everyday routines and appreciate sushi as a form of art. Each piece becomes more than food—it becomes a moment.

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Revision date: June 19, 2025

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Why can’t Sanma (pacific saury) be caught?

On the Pacific Ocean side of Japan there is a three-way deadlock between sardines, mackerel and Pacific saury. There is a theory that the species take turns with increasing and decreasing populations. In recent years there has been an increase in sardines and, in turn, there has been a decline in Pacific saury.

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Revision date: July 30, 2018

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What is the difference between maturing and rotting?

When fish die, stopping the supply of ATP (Adenosine Triphosphate), the source of muscle energy, the muscle fibers gradually harden. As time passes, it gently dissolves and the ATP breaks down, changing into umami components due to self-digestion.

ATP is broken down as follows, but in living fish, only the reaction up to AMP occurs. Once broken down to AMP, it is regenerated as ATP.

ATP→Adenosine diphosphate (ADP)→Adenosine monophosphate (AMP)→inosinic acid (IMP)→hypoxanthine riboside (HxR)→Hypoxanthine (Hx)

In fish after death, inosine monophosphate (IMP) is produced from AMP by an enzyme called adenosine deaminase (ADA). This is called maturing. Inosine monophosphate is not found in cells immediately after death. Maturation is required for the production of inosine monophosphate. If it goes further, it will go bad and HxR (inosine) and Hx (hypoxanthine) will be produced.

The umami created by self-digestion of ATP is “maturing (Jukusei)” and the process after that is “rotting.”

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Revision date: March 17, 2025

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Sushi trends

Foods made to go well with alcohol like ‘shiokara’ salted fish parts or dried mullet roe, don’t go well with shari (vinegar rice). Also, restaurants mainly serving alcohol and foods to pair with it are either bars or Japanese cuisine restaurants that may also serve sushi, but not Edo-style sushi. Many years ago sushi chefs would even get angry saying things like, “Sushi restaurants are not bars. If you want to drink, go next door!” Even Rosanjin wrote, “Sushi restaurants that served alcohol first appeared after WWII. Before the war sushi was served with tea.” In other words, Edo-style sushi restaurants originally didn’t serve alcohol. Perhaps it is true that the increase in sushi restaurants that feel like bars is a natural progression with time.

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Revision date: July 9, 2018

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What are good sushi restaurants!

You can determine how good a sushi restaurant is just by glancing at the topping box (neta-bako). The toppings should all be bright and shiny. This seafood was selected that very morning throughout Tsukiji Fish Market. Even when marinating in vinegar, it’s clear how lively and fresh the fish is.

Every single good sushi restaurant is small. The maximum counter space for a single sushi master to keep up with each customer is 10 seats. These excellent restaurants also have a number of regular customers and almost seem like an exclusive club.

The master conditions his customers to enjoy the toppings that he believes to be the best and the customers train the master into making the dishes they like. After all, making sushi may be a single profession, but it is a relative business and it takes time to build this deep understanding between the chef and customers.

Good sushi chefs do not play favorites to their regular customers. Good regular sushi customers are well-mannered and don’t make an unpleasant atmosphere for first-time customers. Both the chefs and customers are educated in this way. There is this sense of pure pressure in the restaurant.

Good sushi restaurants close their doors early. They need to get to Tsukiji Fish market first think in the morning. This means they need to get to bed by midnight. So the regular customers at these restaurants get up to leave when closing time rolls around. Somewhere along the way they’ve been trained to do this.

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Revision date: June 25, 2018

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What are Meji, Chubou and Maguro?

A photo of Meji — Meji is less than 1 year old and weighs around 20 kg.

The bluefin tuna goes by different names in Japanese depending on its age. It starts out as “Meji (メジ or メジマグロ),” grows into “Chubou (中坊)” and finally is called Maguro or Shibi (once it’s 50 kg or more).

Meji is less than 1 year old and weighs around 20 kg. The term “Meji” is primarily used in the Kanto region. In the Kansai region, it is called “Yokowa (ヨコワ).” Bluefin tuna have ring-like spots on their sides during their juvenile stage, which disappear as they mature. The regional name for the juvenile stage, “Yokowa” (where “Yoko” means “side” and ‘wa’ means “ring”), derives from these spots.

Chubou is an old word for relatively low-class Buddhist priests who were treated as errand boys. I guess it was meant to imply that these boys were even weaker than tuna. At this stage, the fish are between 2-5 years old and weigh about 40kg.

Anything larger than that is called Maguro. The biggest is 3m long and 600kg or more. Especially large tuna is called Shibi. “Shibi” comes from the Japanese characters for “4-days”, which is how long the fish takes to mature.

From late November, Meji fixed net fishing begins in Himi and Sado in the Hokuriku region. Similarly, fishing starts in Shiogama and Kamaishi in the Sanriku rerion, with the peak season for Meji fishing occurring from December to February. In early summer, Chubou begins to be caught off the Sanriku coast, reaching its peak season from May to July. This spring’s tuna schools migrate through the Boso Peninsula and cross the Pacific Ocean. The juvenile bluefin tuna fishing season from spring to early summer comes to an end.

Meji has a unique scent and taste that sets it apart from full-grown tuna. The color is similar to the skipjack rather than bluefin. On the other hand, Chubou has a lighter color and it isn’t as rich, but the flavor is young, refreshing tuna. That is why Meji is considered to be a completely separate sushi topping and Chubou is presented to be a type of tuna.

Category: Edomaesushi

What is Kakushiaji?

A list of Kakushiaji

Related contents:

What is Umami?

Is the handmade ginger in quality sushi restaurants free?

How to Make Gari (Pickled Ginger)

What is the difference between “鮨,” “鮓” and “寿司” (all ready “Sushi”).

Do you know the difference? Most Japanese people don’t know the answer to this question.

Assessing Fish at the fish market!

Why do sushi chefs make the sushi in front of the customers?

There are two ways to make anago nigiri sushi, “skin-up ” and “skin-down”.

The migrating route of Inshore Pacific bluefin tuna and fishing place!

Tuna is matured to rest before it is used.

Why do most sushi restaurants have 8 seats at the counter?

Why can’t Sanma (pacific saury) be caught?

What is the difference between maturing and rotting?

Sushi trends

What are good sushi restaurants!

What are Meji, Chubou and Maguro?