Honyaki is the pinnacle of kitchen knife. Different from Kasumi knives which are constructed using a core-steel (hagane) and a softer cladding (jigane), the honyaki knvies are forged using one single high carbon steel. The knives are differentially-hardened just like the smauri swrods (katana). There are two types of quenching agent: aruba (oil) and mizu (water), mizu-honyaki is the more difficult to forge, requiring high level of skill and experience to pull off, there are very few master in Japan that are able to forge honyaki knives now.
I love honyaki knives, I like them because of their rarity, because they are truly the art of tools and because they really demonstrate the bladesmiths ultimate skill and his full spirit of blade forging.