Konosuke ZDP189 Here is a brand new line of knives from Konosuke. These gyutos are made with ZDP189 steel which is considered a really fine steel. It has extremely high carbon and chromium content but the exact formulation is kept proprietary by Hitachi. Some makers heat treat this steel up to 67-68 HRC but these are heat treated at 65-66 HRC. The knives are solid not clad and take a wicked edge.