Hatsukokoro ZDP-189 Migaki Petty 150mm

A petty knife is a small Japanese utility knife, typically with a blade between 120mm and 180mm, designed for precision tasks like peeling, trimming, and slicing fruits and vegetables. You need one when your main chef’s knife feels too large for detail work, think deveining shrimp, cutting garnishes, or any in-hand peeling where a bigger blade gets in the way. Its slightly longer and slimmer profile than a Western paring knife gives you more control for intricate cuts without sacrificing the nimble feel you want for small jobs. If you regularly find yourself reaching for a smaller blade for finishing work, a petty fills that gap cleanly.

A petty is not a replacement for a gyuto or santoku. It lacks the blade length and belly for efficient chopping, rocking, or breaking down larger proteins. If your work is mostly bulk prep, like dicing onions or slicing roasts, a petty will feel slow and underpowered. It also won’t handle heavy tasks like splitting bones or prying, so treat it as a precision tool, not an all-rounder.

The petty’s role in a Japanese kitchen is as the smaller counterpart to the gyuto, built for tasks where a full-size blade is clumsy. At Knives and Stones, the petty category covers a range of steels including VG10, White#2, Swedish Steel, VG5, SG2, and MV, from makers like Sakai Takayuki, Masamoto Sohonten, Ryusen, Nigara, Hatsukokoro, and Sentan. Most are double-beveled, and the blade length runs from 120mm to 180mm, which is what gives it that balance of reach and precision. For more on how this fits into your knife kit, see the Knives and Stones Education Centre.

Petty knife lengths vary by maker: KAI's guide defines a petty (ペティナイフ) as a small knife with a narrow blade measuring 150 mm or under. Its table gives 90 to 150 mm, and it describes the shape as a smaller gyuto with a pointed tip.

We list petty knives from 70 mm to 165 mm, including lengths above the limit used in KAI's guide.

ZDP-189 holds an edge longer than any other steel we sell. The price is a blade that chips more easily, takes a long time to sharpen and is only modestly rust resistant. It's a specialist's steel, and we wouldn't make it your first Japanese knife, or your second.

The good:

• Edge life. In Knife Steel Nerds' CATRA testing it lasted about 162% as long as 440C, well past SG2. On a board full of meat and tendon it keeps cutting long after most stainless knives have gone dull.
• Hardness. Proterial gives a hardening hardness of over 65 HRC, so it takes and holds a very fine edge.
• Bite. Roughly 30% of the steel is chromium carbide, more of it and coarser than in SG2, and you can feel the edge grip fibrous protein.

The bad:

• Chipping. At that hardness it won't forgive bone, frozen food, a twist in the cut or a glass board.
• Sharpening. We find it slow on most waterstones, with vague feedback, and much happier on a diamond plate. Given the choice, we'd rather not sharpen it at all.
• Rust. The spec sheet says about 20% chromium, but the 3% carbon ties most of that up in carbides. Larrin Thomas's modelling puts the chromium left in the steel near 6.5%, and in his water test a ZDP-189 sample rusted inside eight hours while SG2 and VG10 stayed clean. Treat it as stainless, not stainproof, and dry it straight after use.

It suits a cook who already sharpens on stones, cuts a lot of protein and treats knives gently. For most people SG2 is the better buy. We call SG2 the goldilocks of high-performance cutlery steels: a little softer than ZDP-189, but tougher, more stainless and far easier to keep sharp. Our SG2 vs ZDP-189 page has the full comparison.

ZDP-189 comes and goes in our range. When it's in, it's Hatsukokoro's Hayabusa line and Sukenari's Hairline line.

On Proterial's own figures, ZDP-189 carries 3.00% carbon and 20.00% chromium, with the molybdenum, tungsten, vanadium and cobalt figures kept closed.

Proterial describes it as a stainless blade steel made by a powder metallurgy process, lists its hardening hardness as over 65 HRC, and gives it for custom knives and high-quality cutlery tools.

Hatsukokoro (初心) is a brand, not a forge. H&K, a company founded in 2013 and based in Amagasaki, Hyogo, created it in 2019.

H&K names the producer for some lines, for example Shinkiro by Takahiro Nihei in Fukushima, Ginyou by Yoshihiro Yauji in Echizen and Kurosagi by Motokyuichi Hamono in Nagasaki, and keeps others confidential. Some knives we stock carry the maker in the title, such as Hatsukokoro x Yoshikane SKD Nashiji.

The name comes from the Japanese proverb 初心忘るべからず, which means don't forget your original intention. The company read it gently as hatsukokoro rather than shoshin.

H&K created the brand in 2019, six years after the company was founded, and chose the name for its knife line.

Pick by how much care you want to give. The carbon lines, Blue 1, Blue 2 and AS kurouchi, need drying and a little oil after use. The SG2, HAP40, Ginsan and VG10 lines are low maintenance, so they suit a busy kitchen or someone who just wants to cook.

Neither is better; it depends on your routine. If you will dry and oil the blade after each use, a carbon line can suit you, and if you want the least fuss, a stainless line is the easier choice.