Tetsujin Saku Blue2 So-Kasumi Gyuto 180mm

This Tetsujin Blue 2 So-Kasumi gyuto knife is a 180mm chef’s knife built around Aogami 2 carbon steel, iron clad with a kasumi finish and set on an octagonal wa-handle. At 180mm it is the compact, nimble end of the gyuto range, and it is made by two of the most respected specialists working in Japan today.

Tetsujin is the collaboration between blacksmith Toru Tamura and sharpener Naohito Myojin, both working out of Kochi in the Tosa region, an area with a long and serious reputation for forging. Tamura forges the blade, Myojin puts the final grind and edge on it, and Myojin is the same sharpener behind some of the most sought-after knives coming out of Japan. The result is a blade that arrives thin behind the edge, lightly convexed, and sharper out of the box than most knives ever get.

A gyuto is the Japanese counterpart to the Western chef’s knife, and this gyuto knife is the most versatile blade you can put on a board. The 180mm length is the smaller, more agile option in the range. Where a 210 or 240 gives you reach, a 180 gives you control. It suits smaller hands, smaller boards, and cooks who want a chef’s knife that feels quick and precise rather than long. It still rocks, push cuts, and works through vegetables, meat, and herbs with ease. It just does it in a more compact, manoeuvrable package.

Steel and Construction

The core is Aogami 2, also called Blue 2, a revered high carbon steel that balances edge retention, toughness, and ease of sharpening. It takes a very keen edge, holds it well, and because it is carbon steel it comes back quickly on a stone. Tetsujin hardens it to roughly 62 to 64 HRC, a touch more forgiving and resistant to chipping than harder blue steels while keeping excellent edge retention.

The core is clad in soft iron using san mai construction, where the carbon core is sandwiched between two softer iron outer layers. The kasumi finish shows the contrast between the shiny hard core and the softer misty cladding. Iron cladding is fully reactive, so the whole blade will patina, not just the edge, which is part of the character of a knife like this.

Maintenance and Care

This is an iron clad carbon knife, so it needs proper carbon steel care. Wash it by hand and dry it straight away, every time. Do not leave it wet or sitting in the sink. The blade will develop a patina, a natural greying and darkening across the face, and that is normal and protective rather than a fault. Keep it off bones, frozen food, and hard squash, and sharpen it on a whetstone rather than a pull-through. Treat it right and it will reward you with an edge most knives cannot match.

Best for: cooks who want a compact, agile carbon steel gyuto knife from two of Japan’s finest specialists, and who are happy to give a reactive blade the wipe-and-dry care it asks for.

Kitchen Samurai Ease of Use Rating: 6 out of 10. The blade performance and edge are exceptional, but the fully reactive iron cladding means the whole knife patinas and needs diligent care, so it asks more of the owner than a stainless or semi-stainless blade.

HRC: 62 to 64

Made in Japan.

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