Japanese sword anatomy: blade, hamon, tsuka, and saya parts

Museum labels throw Japanese terms fast. This sword anatomy guide maps parts on a katana (most terms apply to wakizashi and tanto scaled down). Beginners learn what each piece does for cutting, balance, draw, and maintenance—not memorization for trivia alone.

Blade anatomy table

Ji is blade surface between shinogi and hamon. Boshi is temper pattern at kissaki tip—smiths match boshi style to school tradition. Sori (curvature) is not in table but bends draw path—see katana article.

Cross-section shapes

• Shinogi-zukuri—ridge line to edge; standard katana look.
• Hira-zukuri—flat blade; common on tanto.
• Kissaki types—chu-kissaki medium, ko-kissaki small—change thrust point mass.

Mounts table

Full mounted set = koshirae. Fuchi and kashira cap handle ends; menuki ornaments under wrap improve grip feel.

Draw path: habaki and saya mouth

Iai draw needs saya mouth (koiguchi) and habaki tuned—too tight sticks; too loose rattles and cuts saya inside. Seppa washers space tsuba against blade collar. Beginners swinging replicas: check mekugi before each practice—broken peg sends blade flying.

Nakago, mei, and appraisal

1. Remove handle only if trained—museum staff only for antiques.
2. Read mei smith name and date on tang.
3. Compare to known schools (gokaden five traditions).
4. Fake mei exist—expert appraisal required for expensive buys.

Steel zones and forging link

Hada (grain) on ji surface shows folding pattern when polished. Not “layers = sharper magic”—see sword making for tamahagane process. Hamon types (suguha straight, gunome waves) identify schools stylistically.

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