Japanese Knife Anatomy Shinogi Kasumi Ha and the Geometry of the Japanese Blade
Japan (blade craft tradition, centered in Sakai, Seki, and Tosa)
Understanding Japanese knife geometry is prerequisite to understanding their cutting philosophy. The key anatomical features distinguish Japanese knives from all Western equivalents and explain their performance characteristics. The shinogi (鎬) is the lateral ridge running parallel to the spine — the most important reference line on a single-bevel knife. The kasumi (霞 — 'mist') is the hollow or flat zone between the shinogi and the cutting edge on the flat face of a single-bevel knife, deliberately unpolished to appear misty against the mirror-polished ha (刃 — edge). The ha (cutting edge) on a single-bevel knife is formed entirely on one side — typically 70–80° of angle on the right face (for right-handed use), with a minimal ura-oshi (裏押し — back hollow) ground into the flat left face to prevent food adhesion. The kissaki (切先) is the tip, with different profiles for different knives — yanagi tips are angled for pull-cutting, deba tips are reinforced for bone contact. The nakago (中子 — tang) connects blade to handle, with ho (magnolia wood) handles traditional for single-bevel and Western-style ho-ba (magnolia leaf) handles for gyuto.