Parts of a Katana

Every part of a katana has a Japanese name, and knowing them is half of understanding the sword. The diagram below labels them all — free to republish with credit. The gentle curve of the blade itself is called the sori.

The parts, explained

Kashira — the cap at the end of the grip.
Tsuka — the grip: a wooden core traditionally covered in ray skin and wrapped in silk or cotton cord (the ito), producing the diamond pattern.
Nakago — the tang. On a properly made katana it runs the full length of the grip, secured by bamboo pegs.
Tsuba — the guard, often a decorated work of art in its own right.
Habaki — the metal collar at the base of the blade that seats the sword firmly in its scabbard and bears the wear of drawing.
Nagasa — the blade length, measured straight from tip to the notch at the habaki.
Mune — the spine: the thick, unsharpened back of the blade.
Shinoji — the ridge line running the blade's length; this cross-section gives the katana its stiffness.
Ha — the cutting edge.
Hamon — the visible temper line, created by differential hardening: clay-coated spine cools slowly and stays springy, exposed edge cools fast and hardens. Every hamon is unique to its blade.
Kissaki — the tip, polished as its own surface.
Monouchi — the upper third of the edge, where a cut is meant to land.