The general rule is to only eat oysters in months that contain the letter “R”.

In other words, avoid them from May to August.

an image of oysterIt’s won’t hurt you to eat Magaki (Japanese oyster), which has its spawning season in the summer, but in the months with no R in the name, the glycogen concentration is low, so you can’t get the full-bodied texture that you get in winter. In addition, almost all amino acids such as glutamic acid, glycine, alanine, arginine, which are important components for delicious flavor, are known to accumulate from winter through spring, and conversely, they decrease in the summer, which is the spawning season. You cannot expect the same deliciousness from oysters in summer as you can from months that contain the letter R.

Furthermore, the oyster takes in large amounts of seawater and filters out the plankton for its food. Therefore, in warm seasons it fills up on large volumes of the toxic plankton that proliferates in the sea. Eating toxic plankton can make the oyster toxic and toxified oysters can cause food poisoning when consumed by humans. In addition, in the warmer months, the oyster loses its freshness faster after being harvested, increasing the likelihood of getting a bad one and risk food poisoning. Therefore, it’s best to not go out of your way to eat oysters in summer.

On the other hand, one certain oyster is actually in season in summer.

Iawagaki (Rock oyster) is known as the summer oyster. This type is close to the Magaki, and it lives attached to reefs at depths of 2 to 20 m, deeper than the intertidal zone and facing the open sea. A large Iwagaki has a shell length of 10 cm, a shell height of 20 cm or more and weighs more than 1 kg. However, the edible part is small compared to the size of the shell. It is an oviparous hermaphrodite. Growth is slow at a rate of around 5 cm in one year, around 7 cm in two years. It takes three to four years to reach 10 cm or more and grow big enough to harvest.

The glycogen volume in Iwagaki is high from March to July, peaking around May, and it then decreases from September to October. The main production areas are the Sea of Japan on the coasts of Akita, Yamagata, Niigata, and Tottori. Many of the Iwagaki in circulation are harvested from the wild, unlike Magaki, which is almost all farmed.


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Revision date: February 1, 2022

A lesson on how the price of Nigiri sushi is determined

In order to prosper, a business wants to sell products at as high a price as possible. So how does a chef determine the price of nigiri sushi?

Naturally, the cost price is what it costs the restaurant for the ingredients while the price on the menu is the selling price. The ratio of these two prices is called the cost rate. In the case of a sushi restaurant, the ideal cost rate is 35% or less. A restaurant operating with only Omakase will have a cost rate of 40% with a focus on the quality of the toppings.

For sushi restaurants, handling of this ratio and the yield are very important. Yield refers to the part of the purchased fish and shellfish that can actually be used. For example, when purchasing a whole fish there are bones, skin, eyes, tail and internal organs that cannot be served as sushi or sashimi. No matter how good a chef is when preparing fish, the bones and skin will remain. In other words, the yield rate is the percentage of parts that can be used as sushi or sashimi. Typical fish yield rates are as follows:

Wild Maguro (Tuna): 65~75%

Buri (Japanese amberjack): 50%

Hirame (Bastard halibut): 40%

Tai (Red seabream): 35%

Akagai (Ark shell): 25%

Mirugai (Keen’s gaper): 20%

The weight of just the topping for a single piece of nigiri sushi is 12 to 18 grams, depending on the ingredients and the policy of the restaurant. The market price for rice is said to be about US$5 per kilogram, and assuming a weight of 15 grams per Nigiri, the rice for a piece of sushi is generally said to cost about US$0.05, including vinegar and salt. Even if you count the shari (sushi rice), soy sauce, wasabi, nori, etc., it’s fair to consider the cost to be about US$0.10.

Now, let’s figure out the price of Hirame, for which 3 kilograms were bought at $60 per kilogram. Assume that the weight of one topping is 15 grams.

The yield rate of Hirame is 40%, so the chef can make 1,200 grams of sushi toppings from 3,000 grams of Hirame. (formula: 3000 g × 0.4 = 1200 g). Since the weight of one topping is 15 grams, 80 pieces of sushi can be made from 3,000 grams of Hirame (1200 g ÷ 15 g = 80 pieces).

Next, we calculate the cost of one topping. Hirame is US$60 per kilogram, so US$180 (US$60×3 = US$180) for 3 kilogram. Since this volume can yield 80 pieces, the cost of one topping is US$2.25 (US$180÷ 80 pieces = US$2.25).

Add the shari price of US$0.10 to this: US$2.25+0.1=US$2.35. In other words, the cost of one Hirame nigiri sushi is US$2.35.

If the ideal cost ratio of 35% is applied here we get 2.35÷0.35 (35%) = US$6.71. For a restaurant serving mainly Omakase, 2.35÷0.4 = US$5.88.

In summary, one piece of Hirame sushi is sold between $5.88 and $6.71.

It may feel surprisingly cheap, but if you perform these calculations with Kuromaguro or Uni, it will be $60 to $90 per piece, and then you’ll feel that it is too expensive. Therefore, the total margin is secured by setting the cost rate for Kuromaguro and Uni to 80-90%, while the cost rate for Saba and Ika is set to 10-20%.

See Sushiuniversity


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Revision date: January 6, 2022

Is the combination of Chablis wine and Japanese oysters match made in heaven?

White wine is generally thought to go well with fresh seafood.

For example, every Frenchman knows that Chablis wine and Belon oysters go together like peanut butter and jelly. The soil of Chablis is made of the stratum that dates back to the Kimmeridgian age and a unique characteristic is that the soil is rich in fossils of small oysters and shellfish. That is why oysters and Chablis wine are said to be the perfect pairing. However, surely there are Japanese people who sense the fishy odor when having Chablis wine and Japanese oysters (Magaki) together. Therefore, some people say that sake is definitely preferred over wine.

The reason for this is that the types of oysters in France and Japan differ.

Famous for its Belon brand name, the oyster native to Europe has a flat, rounded shell. It belongs to the genus Ostrea. To be honest, Belon oysters aren’t sweet and don’t have a distinguished flavor compared to Japanese oysters, and the salty fragrance of the sea is dulled, so it can seem less flavorful.

Meanwhile, the Japanese oyster is elongated and shaped like a raindrop. It is characterized by a smell like it swallowed the whole ocean. This is the main species farmed in Japan. It belongs to the genus Crassostrea. The taste is as if the umami components of the sea have all been concentrated together in one little shell.

Going back to pairing Chablis wine with oysters, it’s common sense in the world of flavors that items with basically similar components pair well together.

The issue lies in how wine is made. Chablis wine contains lactic acid because it is made through forced mal-lactic fermentation. Because it contains this lactic acid, it is partially fighting against the Belon oyster, which has a high glycogen content. In addition, lactic acid is called “warm organic acid”, and it has the property of becoming delicious at warm temperatures. Oysters are eaten cold, so they aren’t good for taking advantage of “warm organic acids”.

Therefore, it can be said that rather than Chablis wine, it goes well with cold organic acid white wine that is delicious when cooled to 7 or 8 degrees, for example, German Franken wine.

So then, what should be done when pairing oysters with Chablis wine?!

If you insist on pairing oysters with Chablis wine, go all out and add squeezed lemon so the citric acid will work to mask the lactic acid and succinic acid, in turn making the wine taste good even when cold. Citric acid is a “cold organic acid” that becomes delicious when cooled, and oysters rich in glycogen go well with “cold organic acid”. Cold acid-based white wine is abundant in the refreshing “cold organic acids” known as malic acid and tartaric acid. Oysters lack this cold organic acid (malic acid and tartaric acid), so adding the citric acid of lemon creates an exquisite harmony.

However, in France there was a time when a disease spread that caused the death of the Belon oyster, nearly rendering it extinct. Therefore, since the Japanese oyster has been transplanted so many times, it is said that nowadays, at least 90% are Japanese oysters hybrids of Japanese oysters.

That means the question remains among Japanese as to whether the combination of Chablis wine and oysters really is a match made in heaven or not. Personally, we’ve never heard of oysters served without lemon, so the fishy smell really isn’t an issue at all in the end.


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Revision date: January 6, 2022

What is used as a substitute for Madako (Octopus)?

Among the many sushi toppings, Pacific bluefin tuna, and actually the Madai (Red sea bream) as well, are toppings that are difficult for an amateur to tell whether it is farmed or wild. However, there is no need to worry about that when it comes to Tako (Octopus). There are no octopus farms to be found in the world, so it is a 100% wild topping.

In Japan, domestic production isn’t enough to satisfy the appetite of Japanese who like Tako, so the majority relies on imports. Imports from Africa account for 80% and the remainder is imported from China, Southeast Asia, Mexico, Spain and other places in the world.

Most of the African imports are produced by nations on the northwestern coast, with the highest number coming from Mauritania. Until 2003 the highest volume came from Morocco for many years. However, due to continued mass catches to sell to Japan, Tako numbers dropped drastically, leading to the Moroccan government panicking and outlawing fishing. For some reason, Japanese people have grown to love Tako and now consume nearly half of the Tako caught throughout the world.

There are over 200 types of Tako in the world with approximately 60 types inhabiting the seas near Japan. Among these, the Japanese mainly only eat Madako, Mizudako and Iidako. Even among these, Madako makes up at least 80% of consumption.

Most of the Tako found at conveyor belt sushi is African Madako (Madako from Africa). African produced Tako is boiled on-site before being imported frozen. The cost is 20 cents or less per topping.

Amateurs can’t tell the difference between domestic Tako or African imports. However, there is one aspect that even an amateur can use to distinguish between the two. There is one condition for this to work, and that is that at least one of the suckers is in-tact. The suckers are scraped off for most toppings, but in cases where they are sliced by the restaurant, there are often suckers remaining. If the sucker is pure white, it is almost definitely from Africa. Meanwhile, domestic Tako suckers maintain a faint red color in the suckers, even when boiled. The reason the suckers turn white seems to be an effect of the food preservatives added during processing, but this has not been confirmed.

There happens to be a substitute for Madako as well.

One of these is the Iwadako from Vietnam, which grows as large as the height of an adult human. It is imported in frozen slices that can be used as raw Tako as soon as it thaws. The cost of this topping is 20 cents or less per piece. This ends up disguised as Hokkaido Tako.

There are also domestic substitutes. Yanagidako (Chestnut octopus) is mainly caught in the Pacific Ocean, from Chiba prefecture northward. The flavor is lighter than Madako, but it is also softer than Madako, so some people actually consider it to be better than Madako. If it is boiled and made into sushi, an amateur can’t distinguish between it and Madako. The legs are thin so they just need to be cut at an extreme angle in order to make the topping appear bigger. The cost of this topping is 15 cents or less per piece. It is also used as Mizudako because it is watery when eaten raw.

As you can see, there are also many substitute toppings for Madako.


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Revision date: December 21, 2021

CONTENTS

Foreword

How to read this book

History of Nigiri sushi

Classification of Nigiri sushi

1.AKAMI

1-1 Pacific bluefin tuna (Taiheiyou Kuro maguro)

1-1-1 Lean meat of tuna (Akami)

1-1-2 Medium Fatty Tuna (Chutoro)

1-1-3 Very Fatty Tuna (Otoro)

What is Harakami Ichiban?

1-1-4 Meji-maguro

1-1-5 Hachinomi

1-1-6 Kamatoro

1-1-7 Jabara

1-1-8 Chiai-gishi

1-1-9 Wakaremi

What is Hagashi?

1-1-10 Tossaki

1-1-11 Tenpa

1-1-12 Hohoniku

1-1-13 Sunazuri

1-2 Atlantic bluefin tuna (Taiseiyou Kuro maguro)

1-3 Southern bluefin tuna (Minami maguro)

1-4 Bigeye tuna (Mebachi maguro)

1-5 Yellowfin tuna (Kihada maguro)

1-6 Albacore Tuna (Binnaga maguro)

What are Meji, Chubou and Maguro?

1-7 Bonito (Katsuo)

1-8 Striped marlin (Makajiki)

The history of how toro sushi became a superstar!

2.SHIROMI

2-1 Atlantic salmon

2-2 Salmon trout

What is Toro salmon?

2-3 King salmon (Masunosuke)

2-4 Chum salmon (Tokishirazu)

2-5 Chum salmon (Keiji)

2-6 Cherry salmon (Sakuramasu)

Salmon is not used as a topping in Edomae sushi!

2-7 White horsehead (Shiro-amadai)

2-8 Horsehead (Aka-amadai)

2-9 Largehead hairtail (Tachiuo)

2-10 Large-eyed bream (Meichidai)

2-11 Splendid alfonsino (Kinmedai)

2-12 Red seabream (Madai)

What is Red Snapper the same as “Tai”?

2-13 Bastard halibut (Hirame)

2-14 Engawa

2-15 Marbled sole (Makogarei)

2-16 Spotted halibut (Hoshigarei)

How to tell the difference Between Buri, Hiramasa and Kanpachi

2-17 Greater amberjack (Kanpachi)

2-18 Japanese amberjack (Buri)

2-19 Young amberjack (Inada)

2-20 Goldstriped amberjack (Hiramasa)

2-21 Striped jack (Shima aji)

2-22 Japanese spanish mackerel (Sawara)

2-23 Japanese sea bass (Suzuki)

2-24 Chicken grunt (Isaki)

2-25 Filefish (Kawahagi)

When does Kinmedai taste the best?

2-26 Blackthroat seaperch (Nodoguro)

2-27 Tiger puffer (Torafugu)

2-28 Red spotted grouper (Kijihata)

2-29 Bartail flathead (Kochi)

2-30 Sevenband grouper (Hata)

What is Wasabi?

2-31 Longtooth grouper (Kue)

2-32 Japanese butterfish (Ebodai)

2-33 Red gurnard (Houbou)

2-34 Devil stinger (Okoze)

2-35 Green ling (Ainame)

2-36 Red barracuda (Kamasu)

How to use soy sauce under the watchful eye of a Sushi chef

2-37 Barred knifejaw (Ishidai)

2-38 Alaska codfish (Madara)

2-39 Black rockfish (Kurosoi)

2-40 Black seabream (Kurodai)

2-41 Bighand thornyhead (Kichiji)

2-42 Japanese bluefish (Mutsu)

How to Jukusei?

3.HIKARIMONO

3-1 Mackerel (Saba)

3-2 Horse mackerel (Aji)

3-3 Japanese sardine (Iwashi)

3-4 Japanese halfbeak (Sayori)

What is Tsukedai?

3-5 Pacific saury (Sanma)

3-6 Gizzard shad (Kohada)

3-7 Baby Gizzard shad (Shinko)

3-8 Young crimson sea bream (Kasugo)

3-9 Japanese whiting (Kisu)

3-10 Pacific herring (Nishin)

What are Uwami and Shitami?

4.NIMONO

4-1 Common orient clam (Nihamaguri)

4-2 Japanese conger (Anago)

4-3 Japanese eel (Unagi)

4-4 Squilla (Shako)

4-5 Japanese icefish (Shirauo)

Does the taste of wasabi differ depending on the grater?!

5.KAI

5-1 Ark shell (Akagai)

5-2 Japanese abalone (Kuro awabi)

5-3 Giant abalone (Madaka awabi)

5-4 Disk abalone (Megai awabi)

5-5 Ezo abalone (Ezo awabi)

5-6 Japanese egg cockle (Torigai)

5-7 Common scallop (Hotate)

What is Tezu?

5-8 Sakhalin surf clam (Hokkigai)

5-9 Japanese oyster (Kaki)

5-10 Keen’s gaper (Mirugai)

5-11 Round clam (Aoyagi)

5-12 Round clam ligaments (Kobashira)

5-13 Pen-shell (Tairagi)

5-14 Whelk (Tsubugai)

Why is sushi served with Gari?

Types of squid

6.IKA/TAKO

6-1 Bigfin reef squid (Aori ika)

6-2 Golden cuttlefish (Sumi ika)

6-3 Swordtip squid (Kensaki ika)

6-4 Spear squid (Yari ika)

Why is Nigiri sushi eaten with soy sauce?

6-5 Japanese common squid (Surume ika)

6-6 Baby Golden cuttlefish (Shin ika)

6-7 Firefly squid (Hotaru ika)

6-8 North pacific giant octopus (Mizudako)

6-9 Common octopus (Madako)

What is Sute-shari?

7.EBI/KANI

7-1 Kuruma prawn (Kuruma ebi)

7-2 Botan shrimp (Botan ebi)

7-3 Morotoge shrimp (Shima ebi)

7-4 Sweet shrimp (Ama ebi)

Learn the basics of pairing sake with sushi!

7-5 Broad velvet shrimp (Shiro ebi)

7-6 Snow crab (Zuwaigani)

7-7 Horsehair crab (Kegani)

Why did the vinegar used in shari switch from red vinegar to rice vinegar?

8.GYORAN

8-1 Salmon roe (Ikura)

8-2 Herring roe (kazunoko)

8-3 Green sea urchin (Bafun uni)

8-4 Red sea urchin (Aka uni)

Why is it that sea urchin sushi can taste bitter?

8-5 Purple sea urchin (Murasaki uni)

8-6 Short-spined sea urchin (Ezobafun uni)

Hokkaido’s main Ezobafun uni production area

8-7 Northern sea urchin (Kitamurasaki uni)

Hokkaido’s main Kitamurasaki uni production area

8-8 Herring spawn on kelp (Komochi kombu)

The secret story of how Ikura became a sushi topping!

9.OTHERS

9-1 Young Green Onion Shoots (Menegi)

9-2 Shiitake mushroom (Shiitake)

9-3 Daggertooth pike conger (Hamo)

What tea pairs well with Nigiri sushi?

9-4 Oboro

9-5 Monkfish liver (Ankimo)

9-6 Milt (Shirako)

9-7 Omelette (Tamagoyaki)

Does real Edomae sushi no longer exist!?

10.MAKIMONO

10-1 Dried Gourd Shavings Sushi Roll (Kanpyo maki)

What is Kanpyo?

10-2 Tuna Roll (Tekka maki)

10-3 Cucumber roll (Kappa maki)

What is Okonomi?

Sushi Restaurant Etiquette

Sushi Vocabulary and Jargon

Afterword

References

Cooperating sushi restaurant for photography

Copyright

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What is Shiromi?

Hirame is a high-quality fish that goes for at least US $50 per kilogram. It can even exceed US $80 per kilogram, depending on the timing and the fish’s body.

Hirame is a typical shiromi (white meat fish) when winter is approaching and a great sushi topping to start off a meal. Also, the taste is so delicate that the original flavor can be cancelled out just by adding too much soy sauce. How the chef expresses this delicate taste is a tribute to his skill and something that foodies look forward to.

In the US, Hirame is often written as “halibut” on the menu of sushi restaurants. Technically the English name of Hirame is Bastard halibut. Hailbut (referring to Pacific halibut) is called “Ohyo” in Japanese. In Japan, the engawa of massive Ohyo is often used as a substitute for Hirame engawa at conveyor belt sushi, but the two are not confused for each other. There is no mistake that Hirame is related to halibut, but they are completely different species. Incidentally, the price of Ohyo is US $3 to $20 per kilogram. It is incomparably cheaper than Hirame.

Also, depending on the restaurant it may be represented in a variety of other ways such as fluke, flatfish and flounder. These terms refer to relatives of Hirame (鮃) or Karei (鰈), but do not indicate any certain species of fish. In other words, there is generally no distinction between Hirame and Karei in the US and to go even further, all white fish are thought to be the same species.

The delicious taste of fish is dependent on the distribution of fat and the amount of inosinic acid. Therefore, fish taste better in the seasons when they have fattened up. On the other hand, people have a hard time distinguishing between types of fish when comparing the tastes of the parts with less fat. The free amino acids in fish meat differ only slightly between different types of fish. In other words, the flavor of all fish is mostly the same. It is only the amount of fat and the amount of the umami component, inosinic acid, that differ between fish, so apparently even sushi chefs cannot distinguish between fish just by eating the back part, which has a low fat content.

This is part of the reason why in the US all white fish is all lumped into the same category and to top it off, the common consensus there is that white fish has no flavor.

At sushi restaurants in Japan, generally there are at least two types of white fish on offer. It is practically guaranteed that Hirame will be in stock in winter. The light flavor unique to this white meat that spreads with each bite maximizes the aroma and sweetness of the vinegared rice. Recently, white fish with high levels of fat such as Kinmedai and Nodoguro, have become standard, high-quality white fish.

The difference between how even these sorts of white fish are handled in the US and Japan is astonishing. That said, flavorless Hirame is not consumed as sashimi or sushi even in Japan. It is served in dishes with strong flavors, like carpaccio. It’s possible that delicious Hirame is just not available in the US.


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Revision date: July 16, 2022

What is Ishigakigai sushi?

Ishigakigai is a shellfish found from Kashimanada northward, Hokkaido, from the Kuril Islands to the Aleutian Islands and even on the west coast of North America. It lives off of plankton in the shallow sandy mud bottoms of the sea at depths of about 50 meters.

Aquaculture in Hirota Bay, Iwate Prefecture, has been successful and it started to appear at the Tsukiji Fish Market starting in about 2008, distributed as Ishigakigai. According to brokers, someone in the business at Tsukiji Fish Market misheard “Ishikage” as “Ishigaki” and the name stuck in the market. While Torigai meat looks black, Ishigakigai looks whiter, so it is also called “Shirotorigai”. The official name is “Ezoishikagegai”.

It starts to become common at the market when the Japanese rainy season ends, at the beginning of summer every year, which is around the end of the Torigai season. It then disappears from the market at the end of summer. A number of sushi restaurants start using it as a substitute for Torigai all at the same time, so Ishigakigai nigiri sushi suddenly started appearing on menus. Frankly, it is somewhat conservative as a nigiri topping but is known for the crunchy texture when biting into it. It also has strong sweetness and umami, which goes exquisitely with Shari. The sushi chef slaps the meat in his hand directly before serving to stiffen it–a way to increase the crunchy texture characteristic of shellfish. Naturally this texture is evidence of its freshness.

As the season of availability is short and the production sites are limited, Ishigakigai often fetches a high price. Those up for sale at the Toyosu Market go for $2 to $4 each. Wild-caught Ishigakigai is rarely found on the market, but when they are, the price is double that of the farmed version.

A relative of the Torigai, the Ishigakigai is rich in amino acids such as taurine, glycine and arginine. It is also resilient and can live for days, even outside its shell.

Related contents: Ezoishikagegai


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Revision date: October 5, 2021

What is Yamawasabi?

Horseradish is believed to have originated in Eastern Europe. It’s a cruciferous vegetable, alongside mustard, wasabi, cabbage, and broccoli. Horseradish is very fertile, and buds and roots will sprout just by cutting the root stock part to an appropriate size and soaking it in water. Once transferred to soil the roots will multiply quickly even without any other efforts.

In Europe horseradish is used as an ingredient for sauces or to accompany sausage and roast beef, or as a subtle seasoning for other dishes. In Japan most is used as an ingredient in processed foods such as wasabi powder or wasabi paste. Unlike wasabi, horseradish is characterized by its pure white root and strong spicy flavor. In Hokkaido horseradish is called “Yamawasabi” and is a common sight at home dinner tables.

Farming of Yamawasabi for food started in the Meiji era and settled in Hokkaido. Currently over 90% of the domestic production in Japan is accounted for in Hokkaido. While it is grown throughout Hokkaido, the vast Yamawasabi fields befitting Hokkaido are especially prevalent in Abashiri and Kitami.

In Hokkaido, Yamawasabi is eaten as an accompaniment to white rice. Grated Yamawasabi is sprinkled on rice and there are also jars of “Soy sauce-marinated Yamawasabi” sold as a normal item at supermarkets. Besides on rice, it is also indispensable to Hokkaido cuisine as seasoning for hiyayakko (cold tofu) and sashimi.


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Revision date: June 28, 2021

What is Spot prawn?

One type of shrimp that is used for nigiri sushi when still raw is Botan ebi. Needless to say, it is an extremely new addition to the Edomae sushi topping list. Interestingly, there are two types of domestic shrimp that are called Botan ebi in the Toyosu Market.

One is called by its Japanese name, Toyama ebi, with a length of 25 cm, lives in the sea at depths of 100 to 400 m, and is normally caught in Funka Bay of Hokkaido on the Japan Sea side. It actually isn’t caught in Toyama very often despite being called Toyama ebi. At the cheapest it still costs US $20 per kilogram, and in rare cases can exceed $200 per kilogram. In the Toyosu Market, it is called “Torabotan” because of the tiger stripes on the shell (“Tora” is Japanese for tiger).

The other Botan ebi is the Humpback shrimp, which is found on the Pacific Ocean side at depths of 300 m or more and has a length of 20 cm. The main production sites are Suruga Bay, Chiba prefecture and Kagoshima prefecture. The catch is so unstable, and at one point it was almost non-existent, making this shrimp so rare that the Toyosu Market brokers have nearly forgotten about it. The price is even higher than Toyama ebi. In Toyosu, it is called “Honbotan”.

All Botan ebi look beautiful, have a pleasant texture and a mellow sweetness that goes perfectly with shari. Even at high-end sushi restaurants, there is no distinction between the two, and they are both served as Botan ebi.

Considering this, being served substitutes for Botan ebi is unavoidable. About 800 tons of the Spot prawn, found in the northern Pacific Ocean, is imported to Japan from the U.S. and Canada annually. The Spot prawn is a close relative of domestic Botan ebi and they can only be told apart by examining the head closely. It is sometimes called Ama ebi or Botan ebi in the U.S. and Canada. Furthermore, one does not taste better than the other. Especially when eaten raw, the sweetness is intense. The peak season is from April to October, and during this time it is imported live, fresh and frozen.

In the Toyosu Market, it is called Spot ebi and separated from Botan ebi, but is used as Botan ebi in various restaurants and inns. The price is a little lower than the domestically produced but is definitely still an expensive shrimp.


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Revision date: October 5, 2021

What is Rendaku?

In Japanese, when a compound word is made out of two individual words, and the first consonant of the second word changes from a “clear sound” to a “fuzzy sound”, it is called “Rendaku”. For example, Edomae (江戸前) + sushi (寿司) changes to Edomaezushi (江戸前寿司). However, the correct pronunciation is only generalized among Japanese people, so in this book we chose the most commonly searched version of each compound word.

Examples of Rendaku (連濁):

Nigiri (握り) + sushi (寿司)→Nigirizushi (握り寿司)

Inari (稲荷) + sushi (寿司)→Inarizushi (稲荷寿司)

Masu (鱒) + sushi (寿司)→Masuzushi (鱒寿司)

Kaiten (回転) + sushi (寿司)→Kaitenzushi (回転寿司)

Kuro (黒) + tai (鯛)→Kurodai (黒鯛)

Ma (真) + tako (蛸)→Madako (真蛸)

Aka (赤) + kai (貝)→Akagai (赤貝)

Tori (鳥) + kai (貝)→Torigai (鳥貝)

Shiromi (白身) + sakana (魚)→Shiromizakana (白身魚)


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Revision date: June 9, 2021

What is shirakawa?

Out of the five types of Amadai that live in Japan, Aka-amadai, Shiro-amadai and Ki-amadai are the three types offered in the markets.

The main characteristics of Aka-amadai are its overall red body, the bright yellow color under the eyes and how part of its fin is a shiny cobalt blue color. Aka-amadai is called “Guji” in the Kansai region and is a vital part of Kyoto cuisine. Ki-amadai has the same silhouette and size as Aka-amadai, but the Ki-amadai has more yellow color in its face and tail fin. They tend to prefer sandy seafloors at depths of 30 to 300 m and live deeper than any other type of Amadai. True to its name, Shiro-amadai is a white color (Shiro means ‘white’) so is also called Shirakawa (which means ‘white skin’).

Shirakawa is considered to be the finest of the Amadai and can cost more than US $100 per kilogram. Aka-amadai costs around US $40 per kilogram. Shirakawa always ranks in the top three fish for market price. Shirakawa has more elasticity than the other two and has rich fat, making it perfect as sashimi or a sushi topping. The umami is so strong that even when served raw, the customer sometimes thinks it’s been prepared using kobujime. The fat between the meat and the skin is sweet and the skin is delicious in its own right, so it can even be eaten as sashimi with the skin left on. The famous production sites include Tsushima in Nagasaki Prefecture and Yawatahama in Ehime Prefecture. They are in season from autumn to winter. However, they say in a catch of 1,000 Amadai, you can only get one Shirakawa, so it is a rare item you won’t often see, even in a high-end sushi restaurant.


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Revision date: October 5, 2021

Nutritional and Functional components of unagi

According to Japan’s Fisheries Agency, based on their consumer’s behavior survey, Unagi (Eel) always ranks number one under, “Fish Japanese people want to eat.” The highest consumption of unagi throughout the year is in the hot summer months. Since long ago, Japanese people have been captivated by unagi as a food with high nutritional value and have loved it as a measure against heat fatigue. Here We would like to explain the nutritional and functional characteristics of unagi.

Unagi distributed domestically in Japan used to include European eel, but currently, it is mostly Japanese eel. In Japan, the overwhelmingly most popular way to eat unagi is “kabayaki”. Kabayaki mainly refers to a grilled fish cuisine in which unagi or anago (conger eel) is prepared by slicing open along the spine and removing the bones and guts, then skewering it, and grilling without any seasoning, steaming it (Some area, unagi is just grilled longer without steaming. This results in the unagi a little crispier and chewier) after that, and finally dipping it in a sauce made from a mixture of soy sauce, mirin, sugar, sake, etc.

The interesting thing is that the level of free amino acids, deeply related to flavor, is relatively low compared to other seafood. The fatty acid composition and volume don’t change even from heating and it also doesn’t significantly alter the free amino acids, so the flavor of unagi itself is light compared to the flavor of other kinds of seafood. Therefore, this is a big factor in Japanese people thinking of kabayaki sauce when they imagine the unagi flavor.

When the general components of unagi are compared with other fish (flounder, horse mackerel, sardines and bonito) and when they are compared with livestock (cattle, swine, chickens), unagi has the highest caloric content of 255 kcal per 100 g fortis edible parts and it also has the highest fat content (19.3 g per 100 g). Furthermore, it has significantly less fiber than beef or pork, so it is easier to digest. Collagen is present in all vertebrates, but the content is particularly high for eel. Of the minerals contained in the muscles, there is 130 mg calcium for every 100 g, which is much higher than other foods, even higher than milk. There are also abundant amounts of vitamins A, E and B in the meat. 50 g of kabayaki contains more than the recommended daily intake of vitamin A for an adult male and prevents oxidation of the fat, along with vitamin E. Especially high amounts of vitamin B1 are found in all seafood, and vitamin B2 and pantothenic acid contents are also relatively high. Meanwhile, the unagi is also known for having extremely high levels of vitamin A and folic acid in the internal organs.


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Revision date: February 9, 2021

What is the difference between denbu and oboro?

Oboro and Denbu look the same, and the ingredients are also pretty much the same. In other words, there are no clear differences between them, but what it is called differs depending on the restaurant’s policy and the locality. There are various theories for this, but there is no clear line distinguishing oboro and denbu.

Denbu (田麩) is mainly boiled white fish that is then loosened and made into fibers, then seasoned with sugar, mirin, salt, etc., then roasted until the moisture is gone. Some are colored with red food coloring (called sakura denbu) while others are left as the brown color similar to tsukudani. The appearance is as if only the fibers of the original ingredients remain. This is why it was written with the kanji “田夫” (the literal meaning of kanji: rice patty+husband). The word “田夫” means “someone from the countryside” or “rough-cut” and refers to the way the fish is turned into a coarse form by pulling the meat apart. It is also used as a coloring for chirashizushi, futomaki (large sushi rolls), bento boxes, etc.

On the other hand, Oboro (朧) is made by using a grinding bowl to break down the meat of shiba shrimp or white fish, then seasoning with sugar, mirin and salt before removing the moisture over low heat. Oboro is used for bara-chirashi, futomaki (large sushi rolls), etc., and is also sometimes used between the topping and shari (vinegared rice) in nigiri sushi. This gentle sweetness and the shrimp aroma are essential for Edo-style sushi. Making oboro is laborious work, so there are fewer and fewer Edo-style sushi restaurants that make their own oboro.


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Revision date: February 1, 2021

What is Fugu poison?

In most cases, Fugu (blowfish) poison is found in non-meat parts of the fish such as the liver, ovaries, stomach, intestine, skin and eyes. There are Fugu that do not contain poison in these parts, but most of the Fugu in the waters near Japan are poisonous. A mistake in preparations that allows the meat to touch the poison of the liver or ovaries results in immediate death. Therefore, the general rule is to only eat Fugu at restaurants with an expert licensed in Fugu preparation. Cases of poisoning by Fugu are nearly always a result of an amateur trying to prepare the fish.

The toxin in Fugu is a chemical substance called tetrodotoxin and even heat from boiling or frying can’t detoxicate it. Even Torafugu (Japanese pufferfish) that we find so delicious (we eat the meat, skin and testes) has poison in the liver, ovaries and intestines. The toxicity is said to be at least 1,000 times that of potassium cyanide. They say 10 people would die from the organs of a single Torafugu. In the case of Fugu poisoning, the first poisoning symptoms occur between 20 minutes and three hours after eating the Fugu. It starts with numbness in the lips, the tip of the tongue and fingertips. This is followed by headache, stomachache and severe vomiting. The victim will stagger when trying to walk. Soon they will experience sensory paralysis, speech disturbance and difficulty breathing, accompanied by a decrease in blood pressure. After that, the entire body becomes paralyzed and the victim can no longer move even a finger. Finally, they will fade out of consciousness and eventually both breathing and heartbeat cease, resulting in death. If the consumer doesn’t notice they are experiencing poisoning symptoms, they will surely die.

The strength of the toxin of the fugu also varies depending on the season. Even on an individual basis, some fish have toxins while others don’t. It’s not possible to determine this based on appearance, so it’s better to never eat the organs and eyes, which have a high probability of containing poison.

Fugu has already been successfully farmed and is on the market. No toxins have been found in this farmed Fugu. If farmed Fugu has no toxins, it’s only natural to question what factors generate toxins in wild Fugu and apparently it‘s a cumulative effect of toxins from the food chain. Fugu’s main sources of nutrition are starfish and shellfish. Starfish and shellfish accumulate poison in the body by eating zooplankton with vibrio attached to them. This vibrio creates poisons. Then, Fugu accumulates toxins in the body by eating starfish and shellfish that have toxins accumulated in their bodies. Therefore, farmed Fugu are raised on man-made feed that doesn’t contain Fugu toxins, and since they don’t ingest Fugu toxins and there is no bioconcentration, so the Fugu does not contain poison.


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Revision date: February 1, 2021

What is Shusseuo?

During the Edo period, samurai would change their names at Genpuku (coming-of-age ceremony and career stages. Fish that are called by names as they grow older/larger are called “shusseuo (出世魚)”, are considered lucky and are used in cooking to celebrate milestones in life.

Shusseuo doesn’t just change in name, they also change in taste. The bigger the body, the more fat. However, young fish also have their own delicious, refreshing taste unique to their age. For example, using the young fish for deep-frying and fatty fish as sashimi is an interesting way to put it.

Shusseuo is not the only fish called by different names as they grow. According to the “Study of Japanese Fish Names”, there are 82 types of fish that are called by different names as they grow. Kuromaguro and kanpachi are popular examples. Kuromaguro changes from Komeji to Meji to Maguro and then to Oomaguro. Kanpachi changes from Mojako to Shiwoko to Akahana and then to Kanpachi. Even konoshiro, sawara, unagi, shake, koi, etc. are not shusseuo. Generally, it’s not those fish that are called by different names according to their growth stage that is called shusseuo. Fish that taste better as they grow, that changes little over time, and have been valued since eras when preservation and transport were not well-developed, are called shusseuo.

A good representative fish of shusseuo is the yellowtail. Its name changes as it grows and there are various forms of their names depending on the region. In the Kanto region, it changes from Wakashi (15-20cm) to Inada (30-40cm) to Warasa (60cm) and then to Buri (80cm or greater). It is said to be most delicious at 40 cm or longer and even if the body is plump, inada often has little fat.

Even if the name is the same, depending on the region, it may be referring to a different size. For example, inada is a fish up to 40 cm in Kanto but in Tohoku and Tokai, it refers to small fish of 15-20 cm. Further, although it is not related to its growth, those caught in Tohoku during summer are called “ao”. In Toyama, they are called “gan” and “gando”.

Finally, the changing names of fish demonstrate the breadth of culture. We should cherish this local diversity present in the names of our fish that capture the abundant food culture and importance of the seasons.


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Revision date: January 5, 2021