Types of sori of the Japanese sword
The sori of the Japanese sword is the element that, where present, distinguishes the nihontos from the pre-Heian chokuto. The degree of sori and the point of greatest depth vary according to the era in which the blade was forged and can be a good indicator of that era. The sori generally falls into the following classifications:
Torii zori: The word "torii" refers to the portal in front of the Shinto temples. The sori known as torii zori resembles the curved upright of the torii, with an accentuated curvature in the center. It is also called kyo zori, due to the Yamashiro (Kyo) school, which usually produced sori of this type; it is the most used in the Japanese sword.
Koshi zori: The word "koshi" means "waist". The deepest point of this sori is near the munemachi. Also called Bizen zori because it is often used by the schools of this tradition. The tachi produced between the Heian period and the middle Kamakura are usually koshi zori.
Saki zori: "Saki" means "superior". The deepest point of this sori is at the top of the blade. It is generally found in the blades of the Muromachi period. Uchi zori: "uchi" means "inside" or "inward". The uchi zori is opposite to the other sori, towards the hasaki. The much produced during Kamakura are often uchi zori. When a tanto is uchi zori and devoid of fukura, it takes the name of takenoko zori, as it is similar to a bamboo shoot.
Mu zori: "Mu" means "nothing". The term mu zori is used only for the so that have no curvature. Also known as chukan zori, curvature between sori and uchi zori.
