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Motokyuuichi  |  SKU: HSK-KS-GY21BC

Motokyuuichi Kurosagi AS KU Gyuto 210mm Kurouchi by Hatsukokoro Black Chacate

Regular price $199.95

IMPORTANT: Carbon steel knives can rust or patina quickly if not cared for properly. They require regular cleaning, drying, and oiling. If you are unfamiliar with carbon steel maintenance, we recommend choosing a stainless steel option instead.

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Availability

  • St Peters, NSW —
    2 Bishop St, Unit 2, St Peters NSW 2044
  • Crows Nest, NSW —
    107 West St, Shop 1, Crows Nest NSW 2065
    Pickup only
  • Prahran, VIC —
    180 Commercial Road, Shop 1, Prahran VIC 3181
    Pickup only
Detailed Specifications
Line Hatsukokoro Motokyuuichi Kurosagi AS
Profile Gyuto / Chef's knife
Bevel Type Double Bevel
Weight 207 g | 7.3 oz
Edge Length 213 mm | 8 25/64″
Heel Height 50 mm | 1 31/32″
Width @ Heel 2.9 mm | 7/64″
Width @ Mid 2.7 mm | 7/64″
Width @ 1cm from Tip 1.3 mm | 3/64″
Steel Blue Super / Aogami Super | Carbon
Blade Construction Sanmai - Soft Iron Clad
Hardness (HRC) 62 - 65
Surface Finish Kurouchi
Handle Octagonal Black Chacate
Region Nagasaki
Best for
  • Pro chefs
  • Enthusiasts
  • Free shipping for knives over AU$200 Australia wide.
  • World-wide shipping via DHL Express, 3 to 5 days.


This isn’t a knife for Instagram – it’s a hardworking Aogami Super beast with a cult following among chefs who care more about cutting than cosmetics. Master smith Motokyuuichi (of "Tsubaya Black" fame) applies his legendary low-temperature, long-soak heat treatment to Hitachi’s premium steel, achieving a 64+ HRC edge that stays viciously sharp yet resists chipping.

The hand-forged AS core is clad in soft iron, with a deliberately rustic finish – uneven hammer marks, subtle warps, and all. These aren’t flaws; they’re proof of real workshop craftsmanship over factory perfection. Expect stellar food release from the coarser finish, and a thin-but-sturdy grind that handles everything from herbs to squash.

Why it’s a sleeper hit:

→ Unmatched edge retention – "Stays sharp longer than knives twice its price" (Reddit user)

→ Forgiving toughness – Motokyuuichi’s tempering prevents AS’s usual brittleness

→ Zero pretension – No fancy branding, just a fierce cutter that pros quietly recommend

For those tired of overpolined "luxury" blades, this is the anti-status-symbol workhorse – rough around the edges, relentless where it counts.

Pros Cons
  • Budget friendly
  • Excellent performance
  • Workhorse grind
  • Relatively hard to sharpen
  • Prone to rust
  • Fit and finish can be improved
Care Instruction
  1. Don't cut hard things! Japanese knives are brittle so bone hacking is a NO NO!
  2. Wash with neutral detergent after use, and wipe dry;
  3. Please don't wash knife with dishwasher, it will damage the wood handle;
  4. Be careful not to leave the knife close to a heat source for a long time;
  5. It is a lot more dangerous to cut with a blunt knife than a sharp knife!
  6. It is best to sharpen a Japanese knife regularly on a waterstone.
  7. Oil the (carbon) knife if storing for an extended period of time to prevent rust.

Motokyuuichi

Motokyuuichi (本久一刃物), Shimabara, Nagasaki

Motokyuuichi (本久一刃物) is a family forge in Shimabara, Nagasaki, also known as the Maeda forge (前田鍛冶工房). Its own page says the Kyuichi (久一) name flourished among sword smiths in Hizen Shimabara in the Edo period, and that in 1895, as that line faded, the first generation of the Maeda family took over the name and turned the sword forging skills to knives, sickles and hoes.

Read more

The forge's page says the fourth and fifth generations of the family run it today, at the site in Shimabara City where the Maeda family took over the name.

We stock the Kurosagi knives it makes with Hatsukokoro, in Aogami Super with a kurouchi finish.

“A Shimabara family forge that says it took over a sword smiths' name in 1895 and turned to knives.”

Est. 1895 | 明治28年
Known for Kitchen knives from a Shimabara forge with a sword smiths' name
Instagram @motokyuuichi Read more about Motokyuuichi

Motokyuuichi · Nagasaki

Knife details

Frequently asked questions

Gyuto or santoku: which should I choose?

The gyuto came to Japan with the beef-eating culture of the Meiji era, and that is where its name comes from. Tojiro says it is used for all kinds of cooking, which is why it is also called the chef's knife.

The santoku is a household knife that combines the good points of the nakiri and the gyuto. Tojiro describes it as all-purpose, from vegetables to meat and fish, double-bevel and built on the same construction as a Western knife.

Choose a gyuto if you want more length and reach. Choose a santoku if you want a shorter all-purpose knife. Tojiro's own size figures: gyuto 150 to 210mm for household use and up to 360mm for professional use, santoku 165 to 170mm for household use.

What is a gyuto knife used for?

The gyuto (牛刀) is a chef's knife for all kinds of cooking, and it is basically double-bevel. A knife maker's guide says it came to Japan in the Meiji era with the culture of eating beef, which gave it its name, but it does not cut only meat.

A Japanese dictionary describes the gyuto as slimmer than a santoku, with a pointed tip, used widely for meat, fish and vegetables.

What gyuto length should I choose?

A knife maker's guide lists 150 to 210 mm, double-bevel, for home use, and 180 to 360 mm, single- or double-bevel, for professional kitchens.

We suggest starting with a 210 mm gyuto for a home kitchen, and stepping up to 240 mm if you regularly cut large pieces and have the board for it.

240mm vs 210mm gyuto: which size should I choose?

Get the 210mm. We only point people to a 240mm when they have about 45cm of usable board, cook in volume, and regularly break down big roasts or whole fish.

On the gyutos we've measured for our product pages, the extra length is real. As of October 2026, the 210mm gyutos we list have a median edge of 213mm from heel to tip, across the 111 we have measured; the 240mm ones have a median of 240mm, across 100. The 240s are also heavier, 212g against 175g at the median, and a touch taller at the heel, 50mm against 48mm, across the same 100 and 111 knives.

Weight overlaps between the two sizes. As of October 2026, 11 of the 100 measured 240s weigh less than the median 210 at 175g. The 240s we measured weigh 146 to 323g, and the 111 measured 210s 121 to 255g. The number in the name does not decide how heavy a knife is, so check the measured weight on the product page.

Japanese or German kitchen knives: which should I buy?

Our advice: choose a Japanese knife if you want the keenest edge and do not mind caring for a harder blade, and a German knife if you want a tougher, more forgiving knife you can hone casually and use for heavy prep. On two Japanese knife steels, the steel makers' own figures start at 60 HRC: Takefu Special Steel rates VG10 at 60 HRC or more, and Proterial lists the hardening hardness of Aogami 2 (Blue 2) as over 60 HRC.

Our care advice for a Japanese knife: keep it off bone, frozen food and very hard squash, and use a wooden or plastic board.

What is the flat spot on a knife, and is it the same as the "sweet spot"?

The flat spot is the straight run of edge from the heel towards the middle, the part that meets the board along its length. At our counter we call it the sweet spot; elsewhere "sweet spot" often means the balance point, so ask which one someone means.

Past the flat, the edge curves up towards the tip (the belly), which suits a swinging or pulling stroke. Sharpeners also say "flat spot" for a worn patch of edge, so when you mean the shape, "the flat part of the edge" is clearer.

Will a carbon steel knife rust, and how do I look after it?

Yes, carbon steels such as Aogami (Blue) and Shirogami (White) are not stainless steels, so left wet they can spot or rust.

Care is simple once it becomes habit. Wipe the blade as you go, especially after acidic food like citrus, tomato or onion. When you finish, wash it in warm water with a little soap and dry it straight away with a towel. Do not let it air dry, leave it in the sink or the dish rack, or put it in the dishwasher. Store it dry: on a magnetic strip, in a saya or in a block in a dry spot.

If the knife will sit unused for a while, wipe on a thin layer of oil before storing. In our video James shows that mineral oil can stand in for camellia (tsubaki) oil, and he picks one labelled medical grade; we list the Kitchen Knife / Cutting Board Mineral Oil Medical Grade for this. If you find light rust, lift it with a rust eraser and a little water, then dry and oil the blade; we list the CKK and Naniwa rust erasers.

What is Aogami Super (Blue Super) steel?

Aogami Super, also called Blue Super, is a knife steel made by Proterial. Proterial describes it as an alloy steel with tungsten, chromium and vanadium, to improve heat-treatment properties and wear resistance. In its Japanese materials, Proterial calls its Aogami (青紙) steels high-carbon steel (高炭素鋼). Its own figures put carbon at 1.40 to 1.50%, tungsten at 2.00 to 2.50%, vanadium at 0.30 to 0.50% and chromium at 0.30 to 0.50%.

Proterial gives it a hardening hardness of 60 HRC or more. The uses it lists for the grade are high quality planes, other tipped tools, kitchen knives and sickles. Proterial's hardening note calls for quenching in water, with oil as the alternative.

With chromium well under the 10.5% the Japan Stainless Steel Association sets for stainless, it is not a stainless steel. Wipe it dry after use, do not leave it wet or in the sink, and do not leave acidic food on it.

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