Knives for culinary purposes have been made in Japan for centuries, using a technique perfected by Japanese swordsmiths. The blades are sharpened on only one side, ideal for cleanly separating fish flesh from the bone. One of the 50 different types of Japanese kitchen knives is the sword-like "tuna knife." It's 1.5 meters long, and two people are needed to wield it. 90 percent of the knives used by Japanese kitchen professionals are made in Sakai, a city in Osaka. Local artisans in Sakai still make each knife by hand, to order. It took a small Japanese manufacturer five years to perfect the world's first all-stainless-steel knife. Now it exports more than 600,000 knives each year. On this edition of BEGIN Japanology, we explore the long history of Japanese kitchen knives.