Stainless-clad R2 powdered steel with a hammered finish.

Rockwell Hardness ~64.

Handle is ambidextrous quince with brass spacers and a stainless cap. Brass spacers between quince and bolster are loose, which is a flaw from the factory.

Thickness ~2mm

Width (height) ~50mm

The best sharpening tools for Japanese knives are leather strops and fine whetstones.

Takeshi Saji is regarded as a legend in the blacksmithing community of Echizen, Japan. 

Japanese chef knives are brittle and the blades can chip if not handled carefully. High Carbon steel chef knives can rust and corrode if not dried promptly and kept dry.