Moroha-zukuri blades, with a double cutting edge, date back to the early Kamakura Period in the form of ken, which are of symmetrical blade shape. Unsymmetrical tanto such as this, date from the middle and late Muromachi Periods, when they were designed to cut and stab through the weak points in armour. Many were made in Bizen, by smiths including Sukesada, Katsumitsu, and Norimitsu, and some also in Seki. There were later shinshinto copies.