Kotō — Classical Japanese Swords

Kotō refers to swords made before Keichō 1 (1596) in the periodization of Japanese sword history. Excluding jōkotō, it is the oldest orthodox category of Japanese swords and forms the basic concept for appraisal and research. Its antonym is shintō (from 1596 onward), and this dichotomy became established together with the appraisal system set up by the Honami family in the Edo period.

The kotō era can be broadly divided into four phases.

Phase 1 runs from the mid-Heian to the early Kamakura period (around 900 to around 1250). In this period the basic form of the Japanese sword, the curved wantō, was completed. Koshi-zori tachi, derived from warabite-tō, evolved in response to the practical demands of mounted warriors, and the Ko-Bizen, Ko-Hōki and Yamato Gokuha (Five Yamato Schools) formed the early technical peak. In particular, the swords of the Ko-Ichimonji and Awataguchi schools were a rare summit where the aesthetic sense of the Heian aristocracy and the practical philosophy of the warrior class fused. The later appraisal criteria of “shape, steel and edge” (sugata, ji, ha) were established in this period.

Phase 2 is the golden age of the mid-Kamakura period (around 1250 to 1333). Smiths of the Sōshū-den such as Masamune, Yukimitsu and Kunimitsu were active, and the Ichimonji and Osafune schools of Bizen also reached their height. The swords of this period were the most frequent subjects of ōsuriage, the alteration that shortened the blade to suit later demand, and many surviving masterpieces of the mid-Kamakura period have undergone such alteration. The Mongol invasions (1274 and 1281) had a major impact on sword design and promoted innovation in Sōshū-den forging methods, which sought stronger blades.

Phase 3 is the Nanboku-chō period (1333 to 1392). Long, imposing ōdachi appeared, and tachi with blade lengths exceeding 2 shaku 8 sun were produced extensively. Swords of this period overwhelm later generations with their visual grandeur, but few show evidence of actual use, and it is thought that ceremonial and intimidating purposes were strong. Technically, irregular hamon (midare) and great irregular hamon (ōmidare) reached their peak, and this period was a turning point at which Sōshū-den technique spread to smiths across the country.

Phase 4 is the Muromachi to late kotō period (1392 to 1596). The social turmoil after the Ōnin War (1467) fundamentally changed the structure of the sword industry. A mass-production system centered on Osafune in Bizen was established, and practical swords called Sue-Bizen were produced and exported in large quantities. Swords of this period were governed more by the logic of quantity than by artistic precision, though there are not a few masterpieces by individual master smiths, such as those of the Sukesada and Katsumitsu lines and others. The spread of matchlock firearms (from 1543 onward) changed fighting styles and also influenced the design philosophy of swords.

The final phase of kotō (before Keichō) was a transitional period toward Keichō shintō under the Toyotomi regime. Smiths of Keichō shintō, such as Horikawa Kunihiro and Echizen Yasutsugu, inherited kotō technique while incorporating the aesthetic sense of the new era.