Japan (nationwide; Sakai in Osaka and Seki in Gifu as primary knife and stone production centres)
Japanese knife maintenance is a distinct discipline from Western knife sharpening — the asymmetric single-bevel or steep double-bevel geometry, the harder steel (typically 60+ Rockwell hardness), and the thinner blade require specific whetstone technique and care protocols that differ fundamentally from European pull-through sharpeners or coarse bench stones. Japanese whetstones (toishi) are graded by grit: rough repairs at 120–400 grit, basic sharpening at 1000 grit, refinement at 3000–4000 grit, and finishing/mirror polishing at 6000–12000 grit. The fundamental technique requires soaking water stones 5–10 minutes, then maintaining a consistent 10–15° angle (lower than Western knives at 20°) against the stone surface with deliberate forward pressure strokes. Single-bevel knives (yanagiba, deba, usuba) are sharpened almost entirely on one side — the flat ura-oshi (hollow back) restored with just 2–3 light strokes. Between sharpening sessions, a leather strop (kawa-to) removes micro-burrs and realigns the edge. Professional knife sharpeners (toishi-ya) remain active in Japan's major markets and restaurant districts. The nagura stone — a small conditioning block rubbed across the primary stone — creates a slurry of stone particles that accelerates cutting and refines the surface scratch pattern.
Equipment technique — directly determines cutting precision which affects cell structure of ingredients, reducing bruising and oxidation for superior flavour
{"Maintain 10–15° angle (lower than Western 20°) for Japanese knife geometry","Single-bevel knives sharpened 90% on bevel side, 2–3 light strokes on flat back only","Progressive grit system: 1000 grit creates edge, 3000–6000 refines, 8000–12000 polishes","Soak water stones 5–10 minutes before use; splash regularly during sharpening","Nagura stone creates slurry which is kept on stone during sharpening — do not wash off"}
{"Check burr formation by gently dragging thumb perpendicularly across spine side — burr indicates sharpened side","Finish on leather strop with metal polish (chromium oxide) for razor edge refinement","Japanese professional sharpeners charge by stone pass count — watch their hand pressure and angle precisely","For yanagiba sashimi knife: 8000 grit minimum finish; mirror polish at 12000 for premium service"}
{"Sharpening at too steep an angle — creates robust but dull, food-dragging wedge edge","Using pull-through sharpeners on Japanese knives — destroys geometry and chips hard steel","Sharpening single-bevel knives on both sides equally — loses hollow back and ruins cutting geometry","Insufficient stone soaking — dry stone causes uneven abrasion and can crack the stone","Wiping wet stone dry between grits — carry grit slurry through the progression"}
The Complete Guide to Japanese Knives — Various; Japanese Kitchen Knives — Hiromitsu Nozaki