What is "amakuni"

is the legendary swordsmith who supposedly created the first single-edged longsword ( tachi) with curvature along the edge in the Yamato Province around 700 AD. He was the head of a group of swordsmiths employed by the Emperor of Japan to make weapons for his warriors. His son, Amakura, was the successor to his work. Although there are almost no modern examples of signed works by Amakuni, legend has it that the double-edged katana, Kogarasu Maru, was forged by this man. The true author of this work is not known, though the work bears similarities to works of the various Yamato schools so it is thought to be an early example of work from this province.