National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

The early Bizen swords made before the middle of the Kamakura period (1185-1333) are known as "Old Bizen (J., Kobizen)." This long sword (J., tachi) displays characteristics of the Old Bizen, including the following features: the tip is small and straight, the blade surface between the temper line and the ridge appears relatively a white, reflective and cloudy effect (J., midare utsuri), and a temper line that alternately combines clove shapes (J., choji midare) with undulating patterns (J., gunome). They all suggest that Yasukiyo was active in Bizen area (present-day Okayama Prefecture). However, since his name does not appear in directories or any other list of swordsmiths, one theory holds that he worked in Hoki Province (present-day Tottori Prefecture).