The wearing of this decorative, ritual tachi sword denoted the highest rank for a nobleman at imperial court ceremonies. It is distinguished from older tachi, which were usually quite straight, by a slight curve. This is discernible in the raised shinogi ridge-line along the center of the blade. In kogarasu style, only the tip is double-edged: in theory it could be used for both stabbing and slashing. This makes it a valuable resource for understanding the development of the Japanese sword from straight to curved blades. The sword is believed to have been made between the end of the eleventh and the twelfth centuries.