Welcome to Ab Sword. Here's a no-nonsense breakdown of every part on a traditional Japanese katana — the kind of guide I wish I'd had when I first started getting into this stuff.

I get asked about katana anatomy all the time. People see these long listings with terms like "shinogi-ji" and "boshi" and just glaze over. So let me walk you through it. By the end, you'll know your nakago from your yokote.

The Blade

This is what most people care about first. The blade has more named parts than you'd expect.

Sori — the curve

Sori is just the blade's curvature. I won't pretend it's complicated — it's the bend you see when looking at the sword from the side. What matters is how deep that curve goes. A deeper sori changes how the sword moves during a cut. Makes the draw smoother, the slice cleaner. Some prefer a subtle curve, others want more dramatic geometry. Neither is wrong. It's preference and purpose.

Shinogi and Shinogi-Ji — the ridge and the flat

Run your finger along the blade and you'll feel a raised line. That's the shinogi — the ridge. Just behind it sits a flat plane called the shinogi-ji. These aren't just decorative. The geometry adds strength where you need it most and gives the blade that clean, angular look katana are known for.

Hamon — the temper line

Here's where it gets interesting. The hamon is that wavy or straight line running along the edge. It's not etched or painted on — it's real. The smith heats the blade and covers parts in clay before quenching. The covered areas cool slower, stay softer. The exposed edge cools fast, hardens razor-sharp. That's differential heat treatment. Every hamon is different because every smith does this differently. If you want to know if a sword is handmade, the hamon is one of the first things to check.

Boshi — the tip's temper

Boshi is the hamon continuing into the kissaki — the point. Polishing this part takes skill. Get it wrong and you kill the temper. Get it right and the whole blade looks alive. I've seen boshi that look almost three-dimensional under the right light.

Yokote — the tip divider

The yokote is a line separating the main blade body from the tip. Not all katana show this clearly — some styles skip it or soften it through polishing. But most katana you'll encounter display a visible yokote. It's part of what makes a katana look like a katana.

Kissaki — the tip

Kissaki is the point itself. Shapes vary. Some are rounder, some more angular. The shape affects thrusting and how you finish a cut. I won't tell you which is better — that debate has been going on for centuries.

Ha — the cutting edge

Ha is simply the cutting edge. Plain and straightforward. What makes it sharp isn't magic — it's steel quality, heat treatment, and how well it's polished. A well-tempered ha holds an edge through real use. A poorly done one rolls or chips the first time you cut something.

Bo-Hi — the groove

You've probably seen this one mentioned in product listings. The bo-hi is a long groove running along the blade. Does it make the sword weaker? No — done right, it doesn't. What it does is lighten the blade and shift the balance point. Also, when you swing it, air rushes through the groove and makes a sound. Some people love that. Others find it gimmicky. I've cut with both grooved and non-grooved blades and the difference in feel is real, whether you care about the noise or not.

The Tang

Nakago — what's hidden inside the handle

Here's a part most buyers never see. The nakago is the tang — the piece of steel that extends into the handle. On a traditional katana, this is where the smith signs his name. File marks, maker's signature, sometimes the year. It's the blade's ID card.

I think people underestimate how important the nakago is. It determines how the blade connects to the handle, how much vibration transfers during a cut, and how easy the sword is to maintain long-term. A well-designed nakago can be inspected, cleaned, and rewrapped if needed.

The Scabbard

Saya — the sheath

The saya is the scabbard. Simple enough. But here's the thing — a saya isn't just a tube. It's shaped for a specific purpose: fast draw. The interior fit, the wood choice, the lacquer — all of it matters. A sloppy saya means a sword that wobbles or sticks. A well-made one lets you draw clean and fast. Material ranges from basic lacquered wood to high-end options with multiple protective layers.

Kurigata and Shitodome — the cord knob and reinforcement

On the outside of the saya, you'll find a small knob — that's the kurigata. This is where you thread the sageo. Below it, a reinforcement piece called shitodome keeps everything snug. I mention these because they're easy to overlook, but they complete the look and make the sword actually usable when you're wearing it.

Sageo — the cord

Sageo wraps around the saya and ties to your belt. Functionally, it keeps the sword secure. Visually, it's where you can express some style. Different colors, different materials, sometimes matched to the handle wrap. Not a critical part mechanically, but it ties the whole look together.

The Fittings

Now we get into the hardware that holds everything together and protects your hand.

Habaki and Seppa — the collar and washers

Slide the blade out of the saya and you'll see a collar around the base of the blade — that's the habaki. It seats the blade snugly in the scabbard and absorbs shock when you sheathe. Seppa are thin washers on either side of the guard. They take up slack, prevent rattling, and protect the fittings from impact. These parts are often overlooked but they do real work.

Tsuba — Handguard

The tsuba protects the hand and helps balance the sword. Many tsuba are decorative artworks in their own right.

Fuchi — Handle Collar

Fuchi reinforces the handle base and visually complements the kashira at the pommel.

Tsuka-Ito — Handle Wrapping

The tsuka-ito is the cord wrap over the ray skin, made from silk, cotton, leather, or synthetic fibers for grip and comfort.

Same — Ray or Shark Skin

Same under the wrap provides texture and holds the wrap in place while adding strength to the tsuka.

Mekugi — Pegs

Mekugi are small bamboo or wooden pegs that secure the tsuka to the nakago; removable for maintenance but crucial during use.

Menuki — Grip Ornaments

Menuki are decorative fittings beneath the wrap that improve grip and carry symbolic motifs.

Kashira — Pommel Cap

The kashira caps the end of the handle and completes the visual motif with the fuchi, anchoring the wrap and structure.

At Ab Sword, every component — from the blade’s hamon to the handle’s menuki — is crafted and assembled to honor centuries of Japanese swordmaking. Our pages explain these parts so collectors and practitioners can appreciate both form and function.