One of the reasons I went with Kaneshin tools is that they note the type of carbon steel they're using on each tool (with a few exceptions), they use yellow, white and blue paper hitachi steels. I have experience with white and blue steels on both bonsai tools and woodworking tools.
I like blue steel especially for tools I will use on-end with a decent length of time between sharpenings, it's very wear resistant. I like it over stainless because the steel is forge welded to plain iron and therefore the cutting edge can be made harder rather than tempering the hardness lower so that the tool can flex.