Masakage Koishi AS Gyuto 240mm, K&S Hearted-shaped Ironwood Handle

Both are all-purpose Japanese knives, and for most home cooks either will handle the bulk of daily prep. The choice comes down to length, blade shape, and how you like to cut.

A gyuto is the Japanese chef's knife, with a gently curved edge that lets you rock and slide through cuts as well as chop. Tojiro's guide to Western knife shapes gives 150 to 210mm as the household size for a gyuto and up to 360mm for professional use. The extra length and pointed tip give you reach and versatility, from proteins to large produce.

Tojiro's guide to Japanese knife shapes gives 165 to 170mm as the household size for a santoku, which has a flatter profile and a rounded sheep's-foot tip. It rewards a straight up-and-down push cut, feels nimble in smaller hands or tight kitchens, and is the classic Japanese household knife.

Rule of thumb: choose a gyuto if you want one do-everything knife with more reach, or a santoku if you prefer a compact, easy-to-control blade. Plenty of our customers end up owning both.

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.

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.

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.

That length buys you a longer stroke. A 240 goes through a big piece of meat in one or two pulls and moves a board of chopped vegetables with less shuffling. It costs you board space and control. On a small board the tip hangs off the edge, and fine work like herbs and shallots feels like more knife than the job needs.

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.

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.

Yes, carbon steels such as Aogami (Blue) and Shirogami (White) react with food, moisture, and acids, so left wet they can spot or rust. With normal use they develop a grey, blue and brown patina, and that patina is expected on a carbon knife rather than damage.

Aogami has only a little chromium, far below what a stainless steel needs, so water left sitting on the blade will spot it. A patina is a stable oxide layer that slows rust down; orange or red specks are rust.

Care is simple once it becomes habit:

• Wipe the blade as you go, especially after onion, citrus or tomato.
• When you finish, wash it in warm water with a little soap and dry it straight away with a towel. Don't let it air dry or leave it in the sink or the dish rack, and never put it in the dishwasher.
• Store it dry: on a magnetic strip, in a saya or in a block in a dry spot.
• If it's going to sit unused for a while, wipe on a thin film of food-safe mineral oil before storing it.

If you do find rust, lift light orange spots with a rust eraser and a little water, then dry and oil the blade. We stock the CKK and Naniwa rust erasers, and the Koyo Sunlite Polishing Paste (Blue for Steel) lifts light surface rust or refreshes a finish. Rust on the edge itself comes off the next time you sharpen. Deep pitting needs a professional sharpener. Avoid steel wool and harsh scouring on a polished or kurouchi finish, because they scratch it.

On a stainless-clad knife only the thin line of carbon steel along the edge can rust; the cladding stays clean. A carbon-clad or honyaki blade can rust over its whole face and needs the same care all over.

Carbon steel rewards this small amount of attention with a keener edge and easier sharpening than most stainless.

Aogami Blue steel, specifically Aogami Super (Blue Super), is a high-carbon Japanese knife steel made by Proterial that chefs value for its ability to take an extremely sharp edge and hold it longer than most other carbon steels, thanks to a composition with 1.40 to 1.50% carbon, 2.00 to 2.50% tungsten and 0.30 to 0.50% vanadium.

The "Blue" in Aogami refers to the color of the paper the steel is wrapped in at the mill, not the steel itself. Proterial describes Aogami Super as an alloy steel with tungsten, chromium and vanadium to improve heat-treatment properties and wear resistance. Proterial gives it a hardening hardness of over 60 HRC, giving you a blade that can be ground very thin for aggressive cutting performance while still resisting chipping in normal use. The trade-off is that, like all high-carbon steels, it is not stainless: it will rust if left wet or acidic, so you need to wipe it down and keep it dry.