Coincidentally, I was just praising the Kanehiro product. < post44004.html#p44004 >
Not really much of a coincidence as I've lauded them for years. A Kanehiro exemplifies one of my most pragmatic style preferences in Japanese cutlery. They hustle back & forth on the cusp of thin & thick, heavy or light, edge potential & edge retention. They do everything, they do it amazingly well, and they excel at specifics in the twist.
To answer your question. The difference is the hagane... the core steel.. what you cut with. The "AS" is a reactive steel made by Hitachi named "Aogami Super / blue super, in english". The "Ginsan" designates a stainless steel of which is employed in the knifes core. Here is a picture of a Kanehiro AS to illustrate the design. Additionally, the Ginsan may not show this distinction on the spine as they employ a Warikomi style cladding on at least some of the line... you will still see the sandwich in the choil.
The parameters you set in your post eliminate the Ginsan from your list as it is clad stainless steel. You say you want reactive steel, and that is the Kanehiro AS<--link
. The knife is too awesome for me to even offer another suggestion; it would be a disservice. Kanehiro AS is extraordinary.