Kōei-Jōwa Period — The Apex of Nanbokuchō Long Tachi

Nanbokuchō Strife and the Explosion of Sword Demand

The Kōei-Jōwa period (1342–1350) was an age in which the Nanbokuchō internal wars, which intensified after the death of Emperor Go-Daigo (1339), spread across the whole country. The large-scale battles fought between the Northern Court regime of Ashikaga Takauji and the Southern Court led by Emperor Go-Murakami created a demand for weapons on an unprecedented scale. In particular, ō-dachi and ō-naginata were actively forged, as they were valued for their effectiveness in group combat.

The smiths responded to the demands of the warriors and produced extra-long tachi with a blade length (hachō) exceeding 90 centimeters, with some reaching 150 centimeters. These tachi were made not only for practical use but also as votive swords (hōnōtō), and were dedicated to shrines and temples.

Fierce Competition Among the Traditions and the Peak of Technique

In this period, the four great sword traditions—Bizen-den, Yamashiro-den, Sōshū-den, and Yamato-den—competed most fiercely.

The Bizen-den smith groups (Okayama), centered on Osafune, established large-scale production systems and supplied large numbers of long tachi. Kanemitsu, Chōgi, and others reached the height of maturity in this period, producing supreme tachi characterized by magnificent hamon in which chōji mingle with notare, and by fine jihada.

The Sōshū-den (Kamakura) was led by Sadamune, who inherited the legacy of Masamune, and produced tachi with rugged, nie-rich hamon and deep chikei. In the Yamashiro-den, disciples of Rai Kunitoshi were active, and in the Yamato-den as well, the Tegai and Taima schools and others took part in the production of long blades.

Grand Expression of Hamon and Jihada

The most striking aesthetic feature of swords from the Kōei-Jōwa period is the dynamic expression of the hamon. Built on a foundation of notare, many feature large chōji-midare unfolding like billowing waves, with nie and nioi abundantly appearing. The jihada is characterized by flowing itame and a substantial surface quality with chikei running through it, and the entire long blade is complete as a single work of art.

The blades are broad in mihaba, with shallow sori and ō-kissaki, and the long blade gave a visually overwhelming impression. These tachi are highly valued in later ages as works of the Nanbokuchō period, and some have been designated National Treasures and Important Cultural Properties.

Influence on Later Generations

The sword culture of the Kōei-Jōwa period reached one peak in the subsequent Enbun period (1356–1361), and after passing through the Ōnin War (1467–), it shifted to the era of practical uchigatana. However, the image of magnificent sword beauty established in this period continued to be referenced for a long time as an ideal for smiths of later generations.