Katanas are curved, single-edged Japanese swords used by samurai. #katana #samurai #sword - They originated from tantō daggers in the Kamakura period and replaced tachi as the main weapon. #history #Japan - Katanas have a distinct 3D cross-section shape called shinogi-zukuri for speed and cutting ability. #bladesmith - The gentle curve is from differential tempering and gives great cutting power. #forging #blacksmith - Katanas were worn with the edge facing up for quick drawing. #battōjutsu #iai