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

From the end of the Kamakura period (1185-1333) until the Nanbokucho period (1333-92), a school of sword makers in Ukai Village, Bizen province (the present-day Mitsu area in Okayama City) produced swords whose style was slightly different from that of the well-known Osafune school. The Ukai's school's founder was Unsho, whose name is inscribed on this blade. Ukai swords tended to be narrower and less curved than contemporary swords. They have characteristic temper lines along the blades’ edges, including a fine cross-grain pattern (J., koitame), a wave-shaped pattern (J., gunome), and a straight-line pattern (J., suguha) which sometimes has double lines (J., nijuba). These patterns are also common to swords produced in Kyoto. Since these patterns can also be seen in swords of the Aoe school of Bicchu (present-day western Okayama prefecture), there may well have been technical exchanges of some sort between these two schools.