"Tosagata Hocho Cutlery are finely crafted kitchen knives that come from Tosa on Shikoku Island. This Region is much more rural and forested than other parts of Japan, and the blacksmiths still adhere to the old ways. The master blade-maker sandwiches a layer of Aogami Hagane (blue steel) between two pieces of soft wrought iron, and by hand very slowly hammers the blade into shape. Each blade is then individually tempered to Rockwell c63º. Blue steel gives these blades a tough, long-lasting edge unmatched by any Western made knife."
Here’s a map that shows where Tosa is in relation to areas I served on Shikoku. I was never in Kouchi Prefecture (politically like a state, but geographically about the size of a county), but I was in Ehime and Tokushima prefectures, right next to it. Shikoku is very beautiful country.