Most knives are referred to as hōchō or bōchō and there are two classes of traditional Japanese knife forging methods: honyaki and kasumi. These classes are is based on the method and material used in forging a Japanese knife.
Honyaki are true-forged knives made from one material and are considered top-grade knifes made with either blue and or white steel.
Kasumi are made from two materials: high-carbon steel, blue or white steel forged with soft iron. It offers the benefit of being “more forgiving” and generally easier to maintain. Honyaki knives are stiffer and have better duration of sharpness, however they are more difficult to use and maintain as they rust very easily.