Koyanagi 135 mm (5.3 in) Blue#1

• Brand: Ishizuchi
• Construction: Hon-Warikomi / Iron Clad Blue(Aogami) #1
• Method: Hammer Forged
• Blade Length: 135 mm (5.3 in)
• Blade Height: 27 mm (1 in)
• Weight: about 70 g (2.4 oz)
• Spine Thickness: 2 mm/at heel
• Blade Type: Double-bevel
• Core Edge Steel: Blue (Aogami) #1 High Carbon Steel
• HRC (Rockwell Hardness): 61-63
• Finishing: Black Finish (Kurouchi)
• Handle: Japanese, Walnut (Kurumi) with Plastic Ferrule
• Place of Origin: Tosa, Japan

A slim double-bevel Yanagi-type knife for sashimi. Shorter ones (6–13.5 cm) make an excellent substitute for petty knives. Meanwhile, the longer ones (15–21 cm) are best for cooking fish and cutting sashimi at home. Its double-bevel blade works for both right and left-handed people.

Blue (Aogami) #1 (Hitachi Metals Ltd.) is very similar to Blue Steel #2, but the additional Carbon and Tungsten / Wolfram result in even better edge retention and toughness. The steel is perhaps most commonly seen in high-grade Japanese traditional knives.

Black-finish is a state in which the surface that has been blackened by quenching is sharpened only with the blade, leaving the black side unintentionally on the sides (Mine and Hira) other than the blade.

There is no elegance like a polished finish, but it has a taste of bumps and ruggedness. It also has the advantage of being more rust-resistant.