Sori, also pronounced zori, is the curvature of the
Japanese sword, and is always referenced to the mune ('back' of the blade).
It is determined by locating the deepest part of the curvature of the blade
between the kissaki (tip),
and the mune-machi (the notch on the back of the blade where the
habaki seats.)
|

|
Torri-zori (鳥反り)
The deepest part of the curve is at the
center of the blade.

|

|
Koshi-zori (腰反り)
The deepest part of the curvature is between
the center of the blade and the Munemachi. Most early Bizen blades and many
late Kamakura blades have Koshi-zori.

|

|
Saki-zori (先反り)
This is the curve seen most commonly on
Naginata. The deepest part of the curvature is between the center and the
tip of the blade. This sori can be seen in some swords from the early
Muromachi period. These blades are usually described
as 'tending toward' saki sori. The curvature is seldom as
pronounced as it is in this Naginata.

|

|
Uchi-zore (内反り)
When the sword curves the opposite way from
the above shapes, or towards the edge, its called Uchi-zori. Tanto made
during the Kamakura period usually have Uchi-zori.
This is a very slight curvature toward the cutting edge.

|

|
Mu-zori (無反り)
A blade with very little or no curvature has Mu-zori or none.

|

|