Japanese knife steel can be confusing — Shirogami, Aogami, Ginsan, VG-10, SG2, HAP-40… What do all these names actually mean? Let me break them down.

Carbon Steels

Shirogami (白紙) — White Paper Steel

Made by Proterial (formerly Hitachi Metals) in Yasugi, Shimane. Almost pure carbon steel with minimal alloying elements — this means it takes the absolute sharpest edge possible.

  • Hardness: 62–64 HRC
  • Sharpness: ⭐⭐⭐⭐⭐
  • Rust resistance: ⭐ (very low — wipe dry immediately!)
  • Best for: Purists who want the ultimate cutting feel

Available as #1 (highest carbon), #2 (balanced), and #3 (most forgiving).

Aogami (青紙) — Blue Paper Steel

Same Yasuki base, but with chromium and tungsten added for better edge retention. Aogami Super (AS) adds vanadium for even more wear resistance.

  • Hardness: 63–66 HRC
  • Sharpness: ⭐⭐⭐⭐⭐
  • Rust resistance: ⭐ (still low)
  • Best for: Users who want maximum edge retention without going stainless

Stainless Steels

Ginsan (銀三) — Silver 3

A stainless steel from Hitachi Metals with ~14–15% chromium. Takes a fine edge comparable to carbon steel, but doesn’t rust. My personal recommendation for first-time Japanese knife buyers.

  • Hardness: 60–62 HRC
  • Sharpness: ⭐⭐⭐⭐
  • Rust resistance: ⭐⭐⭐⭐⭐
  • Best for: Anyone who wants Japanese geometry without the maintenance

VG-10

Takefu Specialty Steel’s popular stainless. Added cobalt, vanadium, and molybdenum for toughness. Standard in mid-range knives (Tojiro DP, etc.).

SG2 / R2 (SRS-15)

Powder metallurgy stainless from Takefu. Extremely fine carbide structure = high hardness without brittleness. Current state of the art.

Sources: Steel specifications from Proterial (formerly Hitachi Metals), Yasugi Works high-class cutlery steel product page (proterial.com). Takefu Specialty Steel VG-10/SG2 data (takefu-special-steel.com).

Today’s word: 鋼 (はがね, hagane) — steel. The core steel in a laminated blade is called 心金 (しんがね, shingane), while the soft outer cladding is 地金 (じがね, jigane).