Tosa is the name of the area in Kochi Prefecture of Japan, and it is said that the history of forging has been continuing for 400 years ago.
The area of Tosa was warm and rainy, so it was blessed with good quality trees.
The trigger for the development of blacksmith's technique begins with Tosa clan becoming financial difficulties.
They cut many wood to earn income, which required a lot of axes and knives. At that time they increased the skill of forging and became famous as a town of knives that continues to date.