Katana Parts: A Complete Guide To Understanding Every Element Of The Samurai Sword

Legend has it that within every blade lies the memory of its smith: a katana is not just steel; it is a metallic poem, an architecture of balance and function where every piece has a defined purpose. Do you want to understand which parts make up a katana, how they influence its handling, and why every detail matters? This article guides you, with rigor and passion, through the most important katana parts and their history, from the curvature of the edge to the braided silk of the handle.

At a glance: the essential parts of the katana

The katana is composed of three main assemblies: the blade (the cutting soul), the tsuka (the handle that creates the bond between warrior and steel), and the saya (the scabbard that protects and conceals). Between them, a series of minor parts—habaki, tsuba, seppa, mekugi—ensure the integrity and balance of the whole. Below is a detailed guide that breaks down each component and its practical and aesthetic function.

Main Part	Japanese Name	Description
Blade Parts (Ken/To)
Blade length	Nagasa (長さ)	The length of the blade, measured from the Munemachi notch to the Kissaki tip.
Curvature	Sori (反り)	The curvature of the blade, fundamental to its cutting capacity and aesthetics.
Blade edge	Ha (刃) or Hasaki (刃先)	The hardened and extremely sharp edge of the blade.
Back/Spine	Mune (棟)	The blunt back or spine of the blade, opposite the edge.
Ridge line	Shinogi (鎬)	The ridge line running along the side of the blade.
Blade surface (above Shinogi)	Shinogi-ji (鎬地)	The flat surface of the blade above the Shinogi, which is blunt.
Blade surface (between Shinogi and Hamon)	Hiraji (平地) or Hira (平)	The surface of the blade between the Shinogi and the temper line (Hamon).
Temper pattern	Hamon (刃文)	The wavy pattern or temper line visible along the edge.
Longitudinal groove	Bo-Hi (棒樋) or Hi (樋)	A groove carved into the blade to lighten it and improve its balance.
Tip line	Yokote (横手)	A distinctive line that separates the tip (Kissaki) from the rest of the blade.
Blade tip	Kissaki (切先)	The sharp, fan-shaped tip of the blade.
Tip temper line	Bōshi (帽子)	The temper line (Hamon) that extends along the tip of the blade (Kissaki).
Edge curve at the tip	Fukura (脹)	The curve of the edge in the Kissaki area.
Cutting area	Mono-Uchi (ものうち)	The cutting area of the blade, approximately 9 cm from the Kissaki.
Tang	Nakago (茎)	The narrow, unpolished extension of the blade that fits into the handle.
Smith’s signature	Mei (銘)	The swordsmith’s signature, engraved on the Nakago.
Peg hole	Mekugi Ana (目釘穴)	Holes in the Nakago to secure the blade to the handle.
Edge notch	Hamachi (刃区)	The notch on the edge side that divides the blade from the Nakago.
Back notch	Munemachi (棟区)	The notch on the back side that divides the blade from the Nakago.
Blade material	Jigane (地鉄)	General term for the blade material.
Steel surface pattern	Jihada (地肌)	The visible pattern of the steel, resulting from folding during forging.
Handle Parts (Tsuka)
Ray skin	Same (鮫)	Ray skin covering the wooden core of the Tsuka, providing grip.
Braided cord	Tsuka-ito (柄糸)	Braided cord that wraps the handle, adding grip and aesthetics.
Cord knot	Maki-dome	The decorative and functional knot at the end of the Tsuka-ito.
Decorative pieces	Menuki (目貫)	Small decorative metal pieces embedded under the Tsuka-ito.
Bamboo pegs	Mekugi (目釘)	Pegs that pass through the Tsuka and the Nakago to secure the blade.
Metal ring	Fuchi (縁)	A metal collar at the base of the handle, just before the guard.
Pommel	Kashira (頭) or Tsuka-gashira (柄頭)	The pommel or metal piece that covers the end of the Tsuka.
Scabbard Parts (Saya)
Scabbard mouth	Koiguchi (鯉口)	The entrance of the Saya, where the blade is inserted.
Fastening cord	Sageo (下げ緒)	A cotton or silk cord tied to the Saya to secure the katana.
Loop for Sageo	Kurigata (栗形)	A small raised loop on the Saya where the Sageo is tied.
Kurigata metal pieces	Shito-Dome (鵐目)	Decorative metal pieces fixed in the Kurigata.
Scabbard tip	Kojiri (小尻)	The end of the Saya, opposite the Koiguchi.
Storage scabbard type	Shirasaya	An undecorated wooden mount used for storage.
Joining and Decorative Components
Blade collar	Habaki (ハバキ)	A metal piece that secures the blade inside the Saya.
Metal spacers	Seppa (切羽)	Spacers on each side of the Tsuba to ensure a perfect fit.
Guard	Tsuba (鍔)	The circular guard that protects the hand and balances the sword.
Tsuba Parts
Central hole	Nakago ana	The central hole of the Tsuba through which the Nakago passes.
Area around the hole	Seppa dai	The area around the Nakago ana.
Hole for the pick	Kogai hitsu ana	Hole in the Tsuba for a pick (Kogai).
Hole for the knife	Kozuka hitsu ana	Hole in the Tsuba for a small knife (Kozuka).
Blade area near the Tsuba	Tsuba Moto	The area of the blade close to the Tsuba.

The blade: anatomy, geometry, and key terms

The blade is the technical heart of the katana. Here, steel microstructures, differential hardening, and geometric design combine to determine its cutting behavior and strength. Understanding its vocabulary will allow you to distinguish a piece by its function and aesthetics.

Nagasa: useful length of the blade, generally between 60 and 80 cm in traditional katanas; it influences reach and balance.
Sori: blade curvature; a larger sori facilitates curved cuts and quick drawing.
Ha (or Hasaki): the cutting edge; this is where the hamon (temper line) is appreciated.
Mune: the back or spine of the blade; its profile provides rigidity.
Shinogi and Shinogi-ji: the ridge (shinogi) and the surface between it and the spine (shinogi-ji) define the blade’s cross-section.
Kissaki: the tip; its shape determines thrusting capability and the geometry of the finish (bōshi and fukura).
Hamon: the temper pattern resulting from differential hardening; it is both functional and decorative.
Hi (bo-hi): longitudinal groove that lightens the blade and modifies its sound when swung.
Nakago: unpolished tang inserted into the tsuka; the smith usually leaves their mei (signature) here.

Comparative table: blade parts and their function

Part	Japanese name	Function	Material/observation
Edge	Ha / Hasaki	Cutting	Hardened steel; temper profile precision
Curvature	Sori	Optimizes cutting and drawing	Result of differential hardening
Back	Mune	Structural rigidity	Can be rounded or peaked
Tip	Kissaki	Thrusting and cut finish	Includes yokote and bōshi
Groove	Hi / Bo-Hi	Lightens and modifies balance/sound	Can be decorative or functional
Tang	Nakago	Attachment to handle	Usually bears the mei

The tsuka: grip, control, and symbolism

The hilt is not a mere handle: it is the interface between the practitioner and the blade. Its construction combines wood, skin, cord, and metal to offer grip, durability, and aesthetics. Every layer has a reason for being.

Tsuka: wooden core that supports the structure.
Same / Samegawa: ray or shark skin placed over the wood; prevents slipping and distributes tension.
Tsuka-ito: wrapping braided over the samegawa; its pattern and material affect grip and appearance.
Menuki: ornamental pieces placed under the tsuka-ito; often symbolic and useful for hand positioning.
Fuchi and Kashira: the metal collar and pommel that frame the tsuka and seal the braiding.
Mekugi and Mekugi-ana: pegs and holes that fix the tsuka to the nakago; fundamental for structural safety.

Practical details to understand the tsuka

The type of tsuka-ito (silk, cotton, leather, or synthetic) and the braiding pattern will influence the feel when handling the sword. A tighter braid offers a firm grip in combat, while looser variants result in a more ornamental finish.

Joining and protection elements: habaki, tsuba, and seppa

These seemingly small components play a vital role in the stability and safety of the weapon. The habaki seats the blade within the saya; the tsuba protects the hand and balances; the seppa adjust tensions and prevent looseness.

Habaki: wedge-shaped piece at the base of the blade; prevents lateral movement and ensures a firm fit.
Tsuba: the guard that protects the hand; it can be simple or profusely decorated, and its weight affects balance.
Seppa: metal washers that adjust the assembly between tsuba and tsuka; they act as fine shock absorbers.

Saya and external accessories

The saya is not a simple tube: its finish, weight, and fit with the blade determine the ease of drawing and the preservation of the edge. Additionally, pieces like the koiguchi, the kurikata, and the sageo complete its functionality.

Saya: scabbard, usually made of lightweight lacquered wood to protect the blade.
Koiguchi: reinforced mouth of the saya, often made or finished in horn or metal.
Kurikata: small protrusion where the sageo is knotted.
Sageo: cord that allows the saya to be secured to the warrior’s belt or used ceremoniously.
Kojiri: bottom tip of the saya; protects the end and serves as a decorative finish.

How do the parts influence cutting performance?

The effectiveness of a katana depends not only on the steel but on the harmony between its sections. The length and sori define the type of optimal technique. The hamon and hardening profile condition the edge hardness and core flexibility. The tsuba and habaki, for their part, influence static and dynamic balance.

A katana with a pronounced sori favors semi-circular cuts and quick drawing.
A visible hamon indicates differential hardening: hard edge and flexible core to absorb shocks.
A well-fitted nakago and firm mekugi ensure the sword remains integral under intense use.

Technical table: blade profiles and their advantages

Profile	Description	Advantages
Shinogi-zukuri	Section with a ridge (shinogi) and flat plane between ridge and spine.	Ideal balance between rigidity and edge; common in combat katanas.
High Sori	Marked curvature of the blade.	Better for curved cuts and iaijutsu techniques.
Hi or bo-hi	Longitudinal groove in the blade.	Reduces weight, improves balance, and produces a distinctive sound when swung.

Catalog and replicas: models, assembly, and accessories

Katana replicas seek to reproduce aesthetics and assembly. In some models, elements like samegawa or visual hamon are preserved, although materials may vary. Understanding the parts will help you identify a shirasaya mount, a traditional tsuka, or a worked saya.

Types of assembly

Traditional mount: tsuka with samegawa, tsuka-ito, tsuba, and lacquered saya; suitable for collectors and practitioners of traditional martial arts.
Shirasaya: plain wood mount for storage; protects the blade but is not suitable for combat.
Modern mount: may use synthetic substitutes for tsuka-ito or saya; intended for display or recreational practice.

Maintenance and conservation considerations

A well-cared-for katana ages with dignity; an abandoned one corrodes and loses the history it holds. Traditional maintenance includes cleaning with clove oil, removing dust from the nakago, and storage in a saya with controlled humidity. Avoid practices that damage the hardening or cause unnecessary scratches on the blade.

Clean the blade with a soft cloth and specific oil after every handling.
Check the mekugi and tsuka fit regularly.
Avoid hitting hard metals that may produce micro-cracks in the edge.

Common errors in identifying parts

Many confuse the mune with the shinogi or indiscriminately call any handle fitting a “kashira.” Knowing the nomenclature allows you to evaluate authenticity, assembly, and finish quality.

Don’t confuse the nakago (tang) with the visible part of the blade: the nakago is unpolished and usually bears the mei.
An authentic hamon is the result of hardening; a “painted” hamon does not provide the structural properties of differential hardening.
A very light tsuba may be ornamental but alter the balance of the sword.

Quick table: confusing terms and how to differentiate them

Term	Meaning	How to check
Mune vs Shinogi	Mune is the back; shinogi is the ridge.	Observe the blade’s cross-section: the ridge separates two planes.
Real Hamon vs Decorative Hamon	Real: temper line; Decorative: engraved or painted.	Look for continuity and texture; real hamon appears in the steel profile after polishing.
Authentic Samegawa vs Synthetic	Real ray skin vs plastic imitation.	The texture of small nodules (small dots) indicates authentic skin.

How to read a katana: the smith’s signs

The mei on the nakago, the quality of the polish, and the assembly decisions tell the story of who made it and what it was designed for. A signed nakago, a personalized tsuba, or a defined hamon speak of work with intention.

A legible mei on the nakago can indicate a school or author; compare styles to identify periods and workshops.
The finish of the nakago (patina) reveals age and maintenance.
The selection of the tsuba and menuki often reflect the personality of the bearer.

Summary of key points and final reflection

The katana is a sum of parts where technique, aesthetics, and symbolism meet. From the geometry of the blade to the details of the tsuka-ito, every element influences its performance and the story the sword tells. Knowing the katana parts allows you to recognize quality, understand design decisions, and appreciate the tradition behind every assembly.

If you look at a blade against the light, you will see more than just metal: you will see a map of decisions, a smith’s footprint, and a legacy that survives with every edge. Keep that knowledge and let the next katana you examine tell you its true story.

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