Today, we would like to introduce one of the most important tools in the seafood and culinary industries.

When people think of knives, sharpness and durability are usually considered the most important qualities. However, among the knives used by seafood professionals and chefs, there are some that are not designed primarily for cutting. Instead, they are specially made for opening and processing shellfish.

(By the way, “Yappa” is a traditional Japanese fish market slang term that refers to knives and cutting tools.)

Today, we would like to introduce some of these specialized knives.

Shellfish Knives

In addition to common knives such as deba knives, chef’s knives, and utility knives, there are several knives designed specifically for opening shellfish.

From left to right:

• Pen Shell Knife (Tairagai Knife)
• Mirugai Knife
• Hamaguri / Universal Shellfish Knife
• Oyster Knife

These four are among the most commonly used shellfish knives in Japanese fish markets.

Pen Shell Knife (Tairagai Knife)

The Pen Shell Knife has a distinctive shape with a sharp pointed tip.

The tip is inserted into the adductor muscle—the muscle that keeps the shell closed—and pushed inward to separate it from the shell.

Although it is called a “Pen Shell Knife,” it is commonly used for many large shellfish with deep shells, including scallops and similar species.

Mirugai Knife

This knife is designed specifically for opening Mirugai (Japanese geoduck surf clams).

Its most notable feature is its thick blade and rounded tip.

The knife is inserted from the rear of the shell to cut the lower adductor muscle. The shell is then turned over to release the siphon side. The rounded tip helps prevent damage to the siphon and edible meat during processing.

This specialized design allows the clam to be opened efficiently while preserving its appearance and quality.

Hamaguri / Universal Shellfish Knife
This knife is officially known as a “Universal Shellfish Knife.”
As the name suggests, it can be used for a wide variety of bivalves, including:

• Hard Clams (Hamaguri)
• Ark Shells (Akagai)
• Aoyagi Clams
• Surf Clams (Hokkigai)
• Manila Clams (Asari)

and many other shellfish.

A skilled fish market worker can easily shuck more than ten ark shells per minute using this knife.

Techniques vary from person to person. Some begin from the hinge side of the shell, while others start from the siphon side. In either case, the goal is to separate the adductor muscles while minimizing damage to the meat.

Oyster Knife

Unlike the other knives introduced above, this one is called an “Oyster Knife” because oysters are opened by carefully driving the tip into the shell rather than slicing through it.

Compared to many other bivalves, oysters can be difficult to open because the entry point is not always obvious.

One useful tip is that when an oyster is placed with the hinge facing downward, the adductor muscle is generally located on the left side. By inserting the knife from the lower right side and gently twisting, the muscle can be separated and the shell opened more easily.

In some oyster-producing regions of Japan, experienced workers even place the knife stationary on a workbench and push the oyster itself onto the blade to open it quickly and efficiently.

Specialized Tools Supporting Japanese Seafood Culture

There are many different shellfish knives used throughout Japan, but these four are among the most common in fish markets.

Japan—and indeed the rest of the world—is full of unique tools developed to suit local food cultures and traditions. Exploring these tools offers a fascinating glimpse into the craftsmanship behind seafood preparation.

At Itabashi Trading, we not only export premium Japanese seafood, but also provide professional culinary tools to chefs and seafood professionals around the world.

Let us raise a glass of dry sake to the craftsmen and tools that support our industry.

This is the spirit of Bimi Kyushin — a heart devoted to pursuing great food.

If you have any questions regarding product handling, please feel free to contact us.

 

【Contact us】

Itabashi Trading Co., Ltd

Food Department　

TEL :+81-3-3248-1016（Workday 10:00～17:00）　

FAX :+81-3-3248-1008

Email: shokuhin@itabashi-trading.com