It's no exaggeration to say which the items that Japan is so proud of are in part due to the higher precision and sharpness of those blades. The origin of umbrellas in Japan is claimed to be around the Heian time period (794 - 1185), when they had been introduced https://martinmaqfs.bloggosite.com/43412182/5-essential-elements-for-traditional-japanese-craftsmanship