Enbun Era — The Apex of Nanbokuchō Great-Sword Culture

The Enbun era (1356–1361) was a time when the Nanboku-chō wars grew prolonged and intensified. From the standpoint of Japanese sword form, it is positioned as the period when the ōdachi culture reached its peak. After the collapse of the Shōhei Unification (1352), the rivalry between Nanchō and Hokuchō had flared up again, and fierce fighting continued in various regions, spanning the death of Ashikaga Takauji (1358). This continuation of ceaseless warfare created demand for ōdachi production on an unprecedented scale.

The greatest feature of swords of the Enbun period is their blade length. Compared with mid-Kamakura tachi, they became much longer, and in the Enbun and Jōji periods, ōdachi with blade lengths of 2 shaku 8 sun to 3 shaku 5 sun (approx. 85–106 cm) were also made. Such swords were called ōdachi or nodachi, and they were assumed to be used in a manner close to long-shafted weapons. Many of the famous Nanboku-chō swords that survive were later subjected to ō-suriage, a modification that greatly shortens the tang to reduce the blade length. For this reason, it is difficult to imagine the original form of Enbun-period swords from their current blade lengths alone.

Technically, the Enbun period was when the Sōshū tradition (the technical tradition of Sagami Province and Kamakura) spread most widely across the country. The characteristics of the Sōshū tradition, established by Masamune, Yukimitsu, and Kunimitsu, include hamon styles with strong nie, such as turbulent midare, ō-midare, and hitatsura. Smiths in various regions, including Bizen, Yamato, Mino, and Chikuzen, actively adopted these features and fused them with their local traditions. This gave rise to hybrid styles called "Sōden-" (such as Sōden-Bizen and Sōden-Yamato).

Representative smiths of the Enbun period include Kanemitsu (Bizen), Chōgi (Bizen), and Akihiro (Sōshū). In particular, "Bizen Chōgi" is highly regarded in later appraisals as the peak of Bizen work in the Nanboku-chō period. Its majestic form and the power of its Sōden-Bizen hamon make it a representative example of the aesthetics of Enbun-period swords. In the Mino tradition, the Shizu school flourished around the Enbun period, and a style was established in which Mino smiths independently developed the Sōshū tradition.

The sword culture of the Enbun period left a legacy in two senses for the swords of the later Muromachi, Sengoku, and Edo periods. First, as a technical legacy: the nationwide spread of the Sōshū tradition brought advanced forging techniques to various regions, and the accumulated knowledge became the technical foundation of the sue-kotō and Shintō periods. Second, as a stylistic legacy: the majestic beauty of Enbun-period ōdachi became an object of admiration in later times as the "grandeur of the Nanboku-chō." In the kotō-revival movement of the Shinshintō period, the revival of Nanboku-chō style was also raised as one ideal.