Wikipedia
("Chrysanthemum-straight line"), also "Kiku-ichimoji," often and somewhat erroneously romanized as "Kikuichi-monji," is a collective name given to the Japanese swords made by the thirteen swordsmiths who were in attendance to the Emperor Go-Toba in 1208. Each swordsmith was in attendance to the emperor for a month of the Japanese calendar. The swordsmiths of the Fukuoka School traditionally inscribed only the character "Ichi" (一, one) on the tang as their signature. They further received permission to append the Imperial chrysanthemum crest (菊, kiku) on the tang, thus their swords are known collectively as "Kiku-ichimonji". Go-Toba was interested in the construction of Japanese swords, and so he summoned these swordsmiths, granting them court rank and title, and asked them to share the secrets of the production of higher-quality swords.