Japanese Double-Edged Knives: Hamaguriba vs Shinogi Edge Features and Benefits

Japanese knives are celebrated worldwide not only for their beauty but also for their precision. Among them, double-edged kitchen knives—such as the versatile Santoku, the powerful Gyuto, and the sleek Sujihiki—have become everyday essentials for both home cooks and professional chefs. Yet what truly sets Japanese craftsmanship apart lies in the subtle details of the blade geometry.

One of the most fascinating examples is the Hamaguriba (蛤刃)—often called the convex edge or clam-shell edge. Sometimes, you may come across the term hassaiba online, but this is actually a misreading or mistaken rendering of hamaguriba; there is no such blade style as “hassaiba.” The true Hamaguriba has a gently rounded, convex edge that balances sharpness with durability, making it forgiving for beginners yet highly effective for demanding cuts. In contrast, the Shinogi（鎬） + secondary bevel edge（切刃） prioritizes razor-like precision and effortless food release, favored by professionals seeking ultimate control.

In this article, we explore these two iconic Japanese blade styles through the expertise of RYOTA, master sharpener at JIKKO Knives in Sakai, Osaka. You’ll discover how edge geometry influences not only cutting performance but also the flavor and presentation of food, why sharpening techniques differ, and which style might best suit your own cooking.

What Is a Double-Edged Kitchen Knife? Features and Best Uses

Double-edged kitchen knives, known as ryōba（両刃） in Japanese, are the most versatile blades used in everyday cooking. Because both sides of the blade are sharpened at equal angles, they cut straight without drifting and can be used comfortably by both right- and left-handed cooks. Common examples include the Santoku, Gyuto, and Sujihiki. These knives handle meat, fish, and vegetables equally well, making them the go-to choice for home cooks and professionals alike.

Symmetrical Blade Geometry in Santoku, Gyuto, and Sujihiki

The hallmark of a double-edged knife is its symmetrical geometry—both sides of the blade are ground at the same angle. This ensures the knife enters food cleanly and cuts straight, without veering left or right.

Why this design matters:

• Straight, clean cuts – food keeps its natural shape and presentation.

• User-friendly – equally suitable for right- and left-handed cooks.

• All-purpose versatility – one knife can cover a wide range of daily cooking tasks.
  

Representative double-edged knives and their strengths:

• Santoku – With a shorter blade (165–180mm) and a rounded tip, this is the go-to family knife in Japan. Ideal for everyday tasks from chopping vegetables to slicing meat and fish.　→【JIKKO Santoku knife】
  

• Gyuto (Japanese chef’s knife) – Longer (180–240mm) and slimmer than the Santoku, with a pointed tip for precision. Perfect for cutting larger vegetables and breaking down bigger cuts of meat.　→【JIKKO Gyuto Knife】

• Sujihiki (slicer) – Long and narrow (240–300mm), designed for smooth slicing. Excellent for carving roast beef, ham, or sashimi-grade fish.　→【JIKKO Sujihiki Knife】

Best Foods for Double-Edged Knives and How They Differ from Single-Bevel Blades

Double-edged knives shine as all-rounders, offering stability across virtually all food types. They are especially convenient for home cooks or chefs who want one knife that can “do it all.”

Typical foods where double-edged knives excel:

• Peeling and chopping various vegetables and fruits

• Cutting block meat or chicken into portions

• Chopping leafy greens into even slices

So how do they compare with traditional single-bevel knives, which are often favored by Japanese chefs?

In short, a double-edged knife is the perfect “daily driver,” while single-bevel knives are more like precision instruments crafted for specific culinary traditions.

Why Do Japanese Knives Use Single-Bevel Blades? Cultural and Practical Reasons

Single-bevel knives (kataba 片刃 in Japanese) may seem unusual to those familiar only with Western double-edged blades. However, their design reflects both cultural values and practical needs in Japanese cuisine.

In Japanese cooking, precision and presentation are as important as flavor. Dishes such as sashimi or decorative vegetable cuts require paper-thin slices with minimal cell damage, preserving both the texture and the natural shine of the ingredient. A single-bevel blade, sharpened only on one side, creates extremely clean cuts and allows chefs to achieve techniques like katsuramuki (continuous sheet peeling of daikon) or the long pulling slice of sashimi. These are tasks that a double-edged knife cannot replicate with the same level of finesse.

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There is also a cultural element. Japanese cuisine has a long tradition of craftsmanship, where tools are designed to match specific ingredients and cooking methods. The single-bevel blade became a symbol of this precision—specialized knives for sushi, tempura, and kaiseki dining all developed around it. For this reason, professional chefs in Japan often rely on single-bevel knives to showcase their skills and to honor the culinary tradition.

For international cooks, double-edged knives remain the most versatile choice for everyday use. But understanding why Japan values single-bevel blades provides insight into the artistry of Japanese cuisine and explains why these knives continue to hold a special place in professional kitchens.

Hamaguriba vs Shinogi: Blade Geometry, Sharpness, and Cutting Performance

When we talk about double-edged Japanese knives, the story doesn’t end with “two sides sharpened.” In fact, there are two main styles—Hamaguriba (clam-shell convex edge) and Shinogi with secondary bevels—that feel completely different in the hand. Understanding their geometry can change how your cooking looks, feels, and even tastes.

Hamaguriba (Clam-Shell / Convex Edge): Rounded Strength and Durability

The Hamaguriba is named after its resemblance to the smooth curve of a clam shell. Both sides of the blade gently round toward the edge, creating a subtle convex profile. This shape distributes pressure across the blade and makes it resilient against chipping.

Why chefs love Hamaguriba

• Durability first: With a slightly wider edge angle, the blade resists micro-chips even when tackling dense foods.

• Stable and forgiving: It tracks straight through pumpkins, root vegetables, or big cuts of meat without veering off.

• Confidence under pressure: Even when you apply force, the edge doesn’t wobble or feel fragile.

Best for: hard vegetables (lotus root, carrots), thick cuts of meat, or any prep that demands strength over delicacy.

Shinogi and Secondary Bevel: Precision, Sharpness, and Food Release

The Shinogi line—the crisp ridge separating the flat of the blade from the cutting bevel—is a signature of traditional Japanese knife design. Below this ridge lies the kiriha (cutting bevel), which tapers thinly to the edge. On a double-edged knife, the bevel is mirrored on both sides, giving you balance plus razor-like precision.

Why chefs choose Shinogi geometry

• Unrivaled sharpness: The edge can be honed thin, making it ideal for sashimi-style slices or fine vegetable work.

• Effortless food release: The flat surface under the shinogi means food doesn’t cling as much, keeping cuts clean.

• Sharpening made simple: The bevel sits flat against a whetstone, making angle control easier even for beginners.

Best for: tomatoes, cucumbers, herbs, and delicate proteins—any ingredient where presentation and mouthfeel matter.

Which Double-Edged Knife Should You Choose? Practical Comparison Guide

So which style belongs in your kitchen? It depends on what you value most:

• If you often work with hard, dense foods and want a blade that will last longer between sharpenings, go with Hamaguriba.

• If your cooking highlights visual finesse—paper-thin slices, beautiful plating, or sashimi-like precision—the Shinogi style is your ally.

• If you’re a beginner at sharpening, the Shinogi edge is also easier to maintain.

Here’s a quick comparison at a glance:

Most factory-made Japanese double-edged knives come in the Hamaguriba style—but Shinogi edges exist for those who want that extra precision. And here’s the beauty: with the right sharpening technique, you can even reshape your Hamaguriba into a Shinogi-style edge over time.

For those who want to go deeper, JIKKO collaborates with master sharpener RYOTA in a series of tutorials—worth watching if you want to bond with your knife for a lifetime.

【JIKKO/RYOTA’ｓ Youtube videos】

Sharpening Double-Edged Knives Like a Pro: Methods and Ease Compared

There are several approaches to sharpening double-edged knives, each tailored to the blade’s geometry and intended use. Among the most important are micro-bevel sharpening (Koba), shinogi edge sharpening, and hamaguriba (convex edge) sharpening. Each method alters the knife’s character—shaping sharpness, durability, and food release in different ways. In this section, JIKKO’s professional sharpener RYOTA shares key techniques, advantages, and tips to help both beginners and experienced users understand which edge suits their cooking style best.

Sharpening Techniques: Micro-Bevel (Koba), Shinogi Edge, and Hamaguriba (Convex Edge)

1. Micro-Bevel (Koba)

• Characteristics: A tiny bevel is added at the very tip of the edge, reinforcing its strength.

• Benefits: Enhances durability and reduces chipping, ideal for home use and tougher foods.

• Sharpening Tips: Raise the angle slightly more than usual, apply gentle pressure, and work only the edge tip—just a few strokes per side are enough.

2. Shinogi Edge Sharpening (shinogi + cutting bevel structure)

• Characteristics: A flat, wide bevel from the shinogi line to the edge creates a thin, razor-sharp finish.

• Benefits: Excellent food release and clean, precise cuts—perfect for sashimi or delicate vegetable slices.

• Sharpening Tips: Keep the bevel flat against the stone, maintain a consistent angle, and apply even strokes without excess pressure.

3. Hamaguriba (Convex Edge)

• Characteristics: A gently curved profile from spine to edge that balances sharpness with resilience.

• Benefits: Handles hard ingredients without chipping, offering long-lasting stability during heavy prep.

• Sharpening Tips: Avoid locking into a single angle—slightly shift contact points along the stone to maintain the natural convex shape.

Comparison Table: Sharpening Styles

JIKKO’s “Hiho Series”: Comparing Hamaguriba and Shinogi Knives

The Hiho Series—Hiho (秘宝) meaning “treasuredl” in Japanese—is JIKKO’s original collection that combines over a century of Sakai knife-making tradition with modern design. Much like a hidden gem, this line represents the craftsmanship and artistry that JIKKO treasures most. Known for its distinctive Hiho-style shape and exceptional usability, the series includes multiple models crafted from premium steels and featuring unique edge geometries. Two standout designs are the “King” (Hamaguriba type) and the “Queen” (Shinogi type).

Hiho “King” (Hamaguriba type)

• Steel & Structure: Coreless construction (VG10 + VG2 layered steel) delivers both strength and long-lasting sharpness.

• Blade Form: The hamaguriba convex edge provides excellent resilience, handling hard ingredients with ease while retaining sharpness. The layered steel pattern also offers striking visual beauty.

Hiho “Queen” (Shinogi type)

• Steel: Made with Cobalt Special steel, known for excellent edge retention.

• Blade Form: Defined shinogi line and cutting bevel ensure precise, sharp cuts with great food release. The design also makes sharpening more approachable, especially for those who prefer flat bevel structures.

Comparison Table: Hiho “King” vs “Queen”

[See more of JIKKO’s Hiho Series here]

How Blade Shape and Sharpening Transform Your Relationship with a Double-Edged Knife

Double-edged knives are beloved in both home kitchens and professional settings for their balance and versatility. Yet even within this category, the choice between a hamaguriba (convex edge) and a shinogi + cutting bevel edge can make a world of difference. Each blade geometry shapes not only sharpness and durability but also the way you sharpen and maintain the knife.

Understanding these unique features—and mastering the sharpening style that suits your cooking—becomes the key to enjoying your knife for years to come. By choosing the right blade shape and edge finish, you are not just selecting a tool, but building a long-term relationship with your knife.

At JIKKO, our Hiho Series and other double-edged knives offer a wide range of designs, steels, and blade profiles, so you can find the perfect fit for your culinary journey.

Explore more on the official JIKKO website
Watch the original video by sharpener RYOTA, which inspired this article: