Muromachi-period Bizen work can be divided into three epochs. Oei (1394-1428) Bizen (see lot 24), Eikyo (1429-41) Bizen and the Eisho-Tensho (1504-21, and 1573-92) Bizen, also known as "Sue" (late) Bizen, based on the work of prominent smiths and general styles.
This sword is a joint work by two smiths representative of the Eikyo group: Norimitsu and Sukemitsu. The first Norimitsu is believed to have been a pupil of Nagamitsu during the Kamakura period, but the date on this blade identifies the smith as the fourth generation, known as Gorozaemon. The Sukemitsu is the first generation known as Rokurozaemon no jo, the son of Toshimitsu and father of Ukyo no jo Katsumitsu and Sakyo no shin Munemitsu (for a gassaku wakizashi by these brothers see Christie's, London, Important Swords from the Museum of Japanese Sword Fittings, 10 November, 2004, lot 26). The blade was made at Kojima in the southern part of Bizen on the Inland Sea, just four years after the Kakitsu War in which control of Bizen moved from the Akamatsu clan to the Yamana clan, and at which time it is believed that Norimitsu had worked for the Akamatsu.