Parts of a Katana Explained

Understanding the parts of a katana helps you appreciate the extraordinary craftsmanship behind this sword — and make sense of museum descriptions, auction listings, and collector conversations. Here is a complete guide to katana anatomy.

The Blade (Tou / Ha-mono)

• Ha (刃) — the cutting edge
• Mune (棟) — the spine, opposite the edge
• Hamon (刃文) — the temper line created by differential hardening
• Hada (肌) — the grain pattern of the folded steel
• Kissaki (切先) — the tip
• Yokote (横手) — the line dividing the tip from the body
• Monouchi — the upper third of the blade, optimum cutting zone
• Hi (樋) — a groove along the blade to reduce weight

Reading the Blade

The blade is where a katana’s quality is most visible to the informed eye. The hamon (刃文, temper line) is the most immediately striking feature: a wavy or straight line running along the blade near the edge, produced by the differential clay-coating quenching process. Each school of swordsmiths produced a distinctive hamon pattern — the Soshu tradition’s explosive, complex activity (hitatsura), the Bizen school’s gently undulating wave (notare), the Yamato tradition’s straight line (suguha). Identifying the hamon style is one of the primary tools of sword authentication.

The hada (肌, grain pattern) is visible only in good light and at the right angle. When steel is folded during forging, the layers create a surface structure similar to wood grain — flowing lines called itame (wood board grain), tighter circular patterns called mokume (wood burl), or fine parallel lines called masame. Different schools favored different hada patterns, making them another identifier for attribution.

The Tang (Nakago)

The nakago (茎) is the unpolished portion of the blade that extends inside the handle — the part you never see when the sword is mounted. It is the most important element for authentication and attribution.

Most swordsmiths carved their signature (mei) and often the date of manufacture into the nakago. The mei is carved on the outside face (the face that would be visible when the sword is worn edge-up at the waist) — a traditional convention. When a sword is submitted to the Society for the Preservation of Japanese Art Swords (NBTHK) for authentication, the nakago is examined closely: the shape, the file marks (yasuri-me), the patina of the iron, and the signature style are all assessed.

Original, unaltered nakago are crucial for value. A sword whose nakago has been shortened (to fit a different handle) or whose mei has been transferred from another blade is substantially less valuable than an intact original. Forged signatures — applied to unsigned blades or attributing famous smiths’ names to ordinary swords — have been a problem since the Edo period, and their detection is a specialist skill.

The Fittings (Tosogu)

• Tsuba (鍔) — the hand guard, often a canvas for miniature art
• Fuchi-kashira — collar and pommel cap, typically matching sets
• Menuki (目貫) — ornamental grips set under the wrap, visible on either side
• Habaki (鎺) — the blade collar that holds the sword in the scabbard
• Seppa — washers above and below the tsuba

The tsuba (鍔) became an art form in its own right during the Edo period, when swordsmiths and dedicated tosogu artists competed to produce the most inventive designs in iron, copper, shakudo (a copper-gold alloy that turns deep blue-black), and shibuichi (a silver-copper alloy). Classical themes — landscapes, plants, animals, mythological figures — were rendered in miniature with extraordinary delicacy. Museum collections of Japanese sword fittings are among the most specialized and beautiful in the decorative arts.

The Handle (Tsuka)

The tsuka (柄) is built over a wooden core (typically honoki, Japanese magnolia wood) shaped to grip the nakago. The core is wrapped first in ray skin (samegawa) — dried stingray or shark skin with a rough, pebbly texture that provides grip and prevents slippage. Over the samegawa, silk or cotton cord (tsuka-ito) is wrapped in a diamond pattern, with the menuki ornaments positioned to fall under the palm where they further secure the grip without discomfort.

The wrap pattern — typically the standard diamond cross-wrap (hineri maki) — must be done with tension and precision. A loose tsuka-ito wrap is a safety concern; a poorly done one is immediately visible to any knowledgeable person. The tsuka of a well-made sword will last many decades before requiring rewrapping.

The Scabbard (Saya)

The saya (鞘) is made from magnolia wood in two halves, precisely hollowed to fit the blade’s exact profile, then glued and finished. Most saya are lacquered — in black, brown, or decorative patterns. The critical element is the koiguchi (鯉口, “carp’s mouth”) — the opening where the blade enters. It must fit the blade precisely, holding it securely but allowing a smooth draw. A perfectly fitted koiguchi holds the sword in place by friction alone, without any lock mechanism.

Sword maintenance involves the saya as well: uchiko (打粉) — a fine powder of polishing stone — is applied to the blade for cleaning, and the blade must always be stored in the saya, edge-up, to allow drainage of any moisture. A katana stored outside its saya in a humid environment will begin to rust rapidly.