This Hisamoto White #1 Mizu-Honyaki is old stocks from Morihei located Asakusa-bashi, Tokyo.
Since his older generation, Morihei stocked many tools, knives and natural stones in huge storage, and because storage is too big, sometimes, they lost items and find at very later, this knife is one of the old stocks from that era.
The knife is made by Masatomo which was located in Taito-ku, Tokyo, from around 1970 - 1980. They were one of the last blacksmiths in Tokyo, got retired in the 1990s.
Recently many people say that Blue Steel is the best steel, but many of people who know old knives, they think actually white steel is the best. Blue steel makes your knives more sickness in steel, so it won't chip easily, and because it is easier to quenching, so many blacksmiths are able to make knife easily, main reason of why blues steel knives are more expensive than white steel is, because steel itself is more expensive, and sharpener need to charge more because it takes more time to get sharpen. This white #1 steel is one of the purest carbon steel in the world, so you can make a finer edge, but still easier to sharpen because of less stickiness. Back in old days, the most of the blacksmiths were used this white steel, but recently, many people don't have skills to handling this steel, so blue steel got popular.

This items is avaiable at AI and OM Knives.