About the author
Ernest Barać has been working with sushi and Japanese knives for 18 years. During this time, he has regularly worked with larger tuna, both for his own use and at tuna cutting shows, which he still performs today.
The idea for SharpEdge Maguro Kiri came from this hands-on experience with tuna breakdown: a long, thin and manageable knife designed for precise cuts, better control and use across several stages of breaking down a large tuna.
Born from tuna cutting shows
A tuna cutting show is different from a classic fish market breakdown. The goal is to get from a whole fish to the first piece of sashimi quickly and precisely, so the work has to flow smoothly.
For years, my basic setup was a large 300 mm deba and a smaller garasuki or gyuto. The deba handled the main cuts, while the smaller knife was used for harder and more critical points.
The system worked, but I wanted to complete as much of the process as possible with one knife.
That is where our Maguro Kiri began.
What is a traditional Maguro Kiri?
Maguro Kiri is a professional Japanese knife developed for working with large tuna. Its most obvious feature is its length, but the purpose of the long blade is not spectacle. It allows a cut that simply cannot be made with a shorter knife in one stroke.
Professional Maguro Kiri knives already exist at around 450, 540 and 600 mm, while large oroshi, or long tuna knives, can range from approximately 800 to 1500 mm.
When breaking down a large tuna, the long blade is guided along the backbone and through large muscle sections in one long sliding cut. Instead of making several short cuts, you use as much of the blade length as possible at once. The cut surface stays cleaner, it is easier to follow the skeleton, and less meat is left on the bone. A certain amount of blade flexibility is also important. Professionals use the blade’s flex, not just stiffness or force.
However, a traditional Maguro Kiri is not a universal tool for the whole tuna. Professional fish markets use different tools: a saw for thick bones, a deba for more robust work, a hancho for dividing meat, and a long oroshi for large lengthwise cuts. When quartering large tuna with the longest oroshi knives, two people may even work together.
That is an extremely efficient system in an environment where large tuna are broken down every day.
Outside a professional fish market, the needs are different. A chef, caterer, tuna cutting show performer, or someone who occasionally breaks down a larger tuna still needs the advantages of a long blade, but not necessarily a 1000 mm or longer, highly specialized knife.
It started with a piece of steel
The idea did not start at a computer or on a drawing board.
In our warehouse, I saw a piece of VG-10 with Damascus cladding that immediately caught my attention because of its dimensions. It was long and wide enough that I instantly saw the basis for the tuna knife I wanted to use myself.
That is when I started drawing.
The material largely dictated the basic proportions: approximately 460 mm in length, 45 mm in height and only 2.1 mm thick at the spine.
And those 2.1 mm were the most interesting part.
A traditional Maguro Kiri can be much more massive, but I wanted the opposite: a long blade that does not feel like a heavy bar, but gives you feedback while cutting.
The real answers came only when the knife went into tuna.
How does it hold its line along the backbone? How much can it flex while still being guided precisely? How does it behave when separating loins? How does it cut larger blocks?
That is where the real development begins.
The first version shows what works. The next version fixes what you could not predict on paper.
Geometry
The 465 mm length allows long cuts and portioning larger blocks in one stroke, while the knife still remains manageable for one person.
The height of around 45 mm helps keep the blade stable during horizontal cuts along the bones.
The approximately 2.1 mm spine thickness reduces weight and gives the blade feel and flexibility. When working along the skeleton, it is easier to guide and can better follow the anatomy of the fish.
Some would say that 2.1 mm at the spine is too thin for a knife this long. I say it is exactly right.
Sakimaru tip
We chose a sakimaru profile for the tip.
Part of the reason is visual. A knife like this needs character. But the functional reason matters more.
With a long and thin blade, we did not want a very fine and delicate tip. The rounded sakimaru profile keeps more material at the end of the blade, giving it more robustness during demanding parts of the breakdown, such as cutting through cross bones while filleting.
VG-10, Damascus and 59 HRC
Large tuna means water, ice, blood and salt. During longer work, I do not want to also worry about possible blade oxidation.
With the first version, we tried to push VG-10 as far as possible and heat-treated the blade to more than 60 HRC. The very first tuna showed that this was not the right direction for this type of work.
We repeated the heat treatment and found a much more useful balance between sharpness, edge stability and toughness at approximately 59 HRC.
With a blade this thin and long, a micro chip can still appear during demanding work. That is the reality of this geometry and use case. The knife is not intended for chopping through thick bones.
The final result is a practical tool
Our Maguro Kiri does not try to replace traditional long Maguro Kiri and Oroshi knives used at large Japanese fish markets. Those knives were created for their own environment, workflow and users.
This knife was created for a different need: to combine enough length for working on large tuna with feel, control and usability across a wider range of tasks.
After more than a year of use, several dozen tuna breakdowns and many events, the original idea proved to be very practical.
A big knife for precise cuts and precise hands.
Maguro Kiri is available in two versions: Layered Damascus and Raindrop Damascus.
View both knives here:
SharpEdge Maguro Kiri
