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Otsuka  |  SKU: OTSU-BU-170BC

Otsuka Kurouchi Bunka 165mm Blue 1 Carbon Black Chacate

Regular price $299.95

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.

Add a saya or K&S Knife Roll to receive $20 bundle discount!

Detailed Specifications
Line Otsuka Blue 1 Kurouchi
Profile Bunka
Bevel Type Double Bevel
Weight 126 g | 4.4 oz
Edge Length 168 mm | 6 39/64″
Heel Height 46 mm | 1 13/16″
Width @ Heel 1.8 mm | 5/64″
Width @ Mid 1.7 mm | 1/16″
Width @ 1cm from Tip 0.6 mm | 1/32″
Steel Blue 1 / Aogami #1 | Carbon
Blade Construction Sanmai - Soft Iron Clad
Hardness (HRC) 61 - 64
Surface Finish Kurouchi
Handle Octagonal Black Chacate
Region Other
Best for
  • Pro chefs
  • Enthusiasts
  • Free shipping for knives over AU$200 Australia wide.
  • World-wide shipping via DHL Express, 3 to 5 days.


Otsuka's Blue 1 series is pretty much the only lineup that is offered by Otsuka Hamono, and there is only few profiles included. The Bannou(万能, All-purpose)proile that shape like Bunka is offered in different size which covers pretty much all cutting scenarios, and all these blades are raw, rustic and got significant trace of manual labour on them. But don't get ticked, these knife are some of the best cutting tools you can find at this price.

The first thing you'll notice when picking these knives up is the the extreme taper in the spine. It is noticeably wide than even Anryu's knife and it tapers to sub-millimetre thickness in the front. It doesn't even show in the measurement as the thick spine have already tapers significantly right above the heel. The advantage of this taper is, you can have a very strong and rigid blade at its tang, and the thinner tip can stay sharp and nimble while the entire blade is dampened with some weight. As the result, Otsuka's Bannou are vary responsive and controllable in hand.

Then it comes to sharpening, which is where these blades really shines. Despite the rough Kurouchi look, the bevels actually receives a very high level hand sharpening, which leaves a super thin edge that just melt through potatoes. The secret is the well-controlled convex grind, which reduce sticking and allow the food to glide off the bevel. In addition, the excellent sharpness produced by the carbon steel edge is well utilised to allow very good slicing performance.

I'm surprised this knife haven't got very popular, but I Think it's not necessarily the knife or the community's fault. As Otsuka Hamono is located in a remote village in Tottori prefecture and Otsuka san have decided to embrace the life without internet, his knife is not commonly sourced, purchased or discussed. If you can take care of the carbon steel and appreciate these hand crafted beauties, I highly recommend Otsuka's knife for their amazing cutting performance and handling.

Pros Cons
  • Excellent performance
  • Thin behind the edge
  • Exceptional profile
  • Prone to rust
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.

Otsuka Hamono

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Otsuka Hamono is a relatively small smithy that flew under many's radar. Maybe because that Otsuka san have chosen the life without any internet connection and continues his work in his workshop that is tucked in the mountains of Tottori prefecture. His work is wild to say the least, the kitchen knives pretty much comes only in one shape at different sizes, the spine of them have the most extreme tapering I've ever seen on a Japanese kitchen knives, and they often comes with handles that appears to be some locally found, trimmed tree branches.

If you look at other items that Otsuka san produces, you can find out the root of this wild style. With hatchet, hunting knife and Nepal Kukri combat knife surrounding them, the kitchen knife would be considered as the "tame" ones. As wild as the style goes, Otsuka's knitchen knives are some of the most well built kitchen tool for the task. The afore mentioned thick spine rapidly tapers into a thin blade with a well executed convex grind, giving these knives smooth cut and beautiful feeling in hand. The rough look really is just a facade that display Otsuka san's lifestyle.

Read more about Otsuka Hamono
Otsuka Hamono — Other
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Profile: Bunka
Profile

Bunka

A pointier version of the Santoku. The Bunka knife features a distinctive profile with a straighter edge and a pointed tip, making it versatile for a variety of kitchen tasks. Its design is a blend of the Santoku and K-tip Gyuto knives, with a blade length typically around 165mm to 180mm. The Bunka is particularly adept at slicing, dicing, and chopping fruits, vegetables, and meats, thanks to the precision and control enabled by its length and flat edge profile. The angled tip, also known as a reverse tanto, provides additional precision for intricate tasks such as julienning. With its unique shape and functionality, the Bunka stands out as a multifunctional knife in the culinary world.
Composition

Blue 1 / Aogami #1 Element Composition

Compare with
    Blue 1 / Aogami #1
    1.5% 1.1% 0.8% 0.4% 0
    C Carbon 1.3%
    Primary hardening element. Raises hardness and wear resistance — but too much increases brittleness and corrosion susceptibility. As a reference: German 1.4112 (~0.5%) sits at the low end; VG-10 (~1.0%) is a common mid-range; SG2 (1.25–1.45%) and ZDP-189 (~3.0%) represent high and extreme ends respectively.
    C
    1.3%
    Cr Chromium 0.3%
    Raises corrosion resistance; 13%+ qualifies steel as stainless. Also improves hardenability and wear resistance. In kitchen use, higher chromium levels contribute to a slight drag or sticking sensation when cutting — a trade-off for the rust resistance it provides.
    Cr
    0.3%
    W Tungsten 1.5%
    Forms hard carbides for wear resistance and edge retention. Gives the steel hardness even at elevated temperatures.
    W
    1.5%
    Mn Manganese 0.2%
    Aids hardenability and strength. Acts as a deoxidiser during smelting. Excess can reduce toughness.
    Mn
    0.2%
    Si Silicon 0.1%
    Strengthens the steel matrix and acts as a deoxidiser. Improves hardness and resistance to oxidation.
    Si
    0.1%
    P Phosphorus 0.025%
    Impurity from the smelting process. Even small amounts cause brittleness — steelmakers keep this as low as possible.
    P
    0.025%
    S Sulfur 0.004%
    Impurity that reduces toughness and promotes brittleness. Intentionally added only in free-machining steels.
    S
    0.004%
    C — Carbon Cr — Chromium W — Tungsten Mn — Manganese Si — Silicon P — Phosphorus S — Sulfur
    Hardness 61–64 HRC
    555759616365+
    Steel
    Blue 1 / Aogami #1
    Category
    Carbon
    Manufacturer
    Hitachi Special Steel, Japan 🇯🇵
    Hardness
    61–64 HRC
    Steel

    Blue 1 / Aogami #1

    • Manufacturer
      • Hitachi Special Steel, Japan
    • Nature Carbon
    • Hardness61–64 HRC
    Blue Steel No.1, also known as Aogami #1 or Yasugi #1 Blue Steel, is a premium high carbon steel from Hitachi Metals Ltd, celebrated for its exceptional edge retention and toughness. This steel is an upgrade from Blue Steel No.2, enriched with higher carbon and tungsten content, making it a favorite for high-grade Japanese traditional single-bevel knives. It's known for being easy to sharpen, achieving a very fine edge that lasts. Despite its susceptibility to rust, with proper care and maintenance, including regular wiping and drying, it can develop a protective patina that minimizes rusting. Blue Steel No.1 is highly regarded among knife makers for its ability to achieve a mirror finish and maintain a sharp edge over extended periods, offering an outstanding balance of performance and durability.
    Construction: Sanmai - Soft Iron Clad
    Construction

    Sanmai - Soft Iron Clad

    Sanmai iron cladding is a traditional Japanese knife construction technique where a hard steel core is sandwiched between two layers of softer iron or steel. This method combines the superior edge retention and sharpness of high-carbon steel with the durability and ease of maintenance provided by the softer outer layers. The sanmai structure offers a balanced knife that is both flexible and resistant to breaking, ideal for precision cutting tasks. The softer outer layers also facilitate easier sharpening and contribute to the aesthetic appeal of the knife through the development of a unique patina over time. While sanmai-clad knives require careful maintenance to prevent rust, their exceptional performance and distinctive appearance make them often a desirable feature of Japanese knives.

    Finish: Kurouchi
    Finish

    Kurouchi

    Kurouchi refers to the rustic, unpolished finish found on the blade of many traditional Japanese kitchen knives. This blacksmith's finish is characterized by its dark, textured appearance, which is the result of leaving the blade forge-scale on the steel during production. Kurouchi finish not only adds a unique aesthetic appeal but also provides certain practical benefits. It acts as a protective layer against rust and corrosion, and helps to reduce food sticking to the blade during cutting. Commonly seen on high-quality, hand-forged knives, the kurouchi finish emphasizes the artisanal nature of the knife and its heritage, making each piece distinctively unique.

    Handle
    Handle

    Handle Specs

    • Profile Octagonal WA
    • Material
      • Black Chacate

    Black Chacate is a highly valued timber known for its deep, rich brown to almost black coloration, fine texture, and exceptional durability. It polishes well, offering an exquisite finish that highlights its subtle, elegant grain patterns. This wood is often used in fine woodworking projects, including luxury furniture, decorative items, and high-end knife handles.

    An octagonal wa handle made from Black Chacate wood would exhibit a sleek, geometric shape that fits comfortably in the hand, enhancing the user's grip and control. The deep hues and natural luster of Black Chacate add a touch of sophistication and unparalleled beauty to the handle, making it not only a functional component of a kitchen knife but also a piece of art. The durability and stability of Black Chacate ensure that the handle withstands the rigors of kitchen use while maintaining its aesthetic appeal over time.

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