What is the Kazuuchi-tou: Mass Sword Production in the Muromachi Period and the Reality Born from Warfare

Kazuuchi refers to practical swords mass-produced through simplified processes from the late Muromachi period through the Sengoku period to meet the massive demand created by warfare. These contrast with "chumon-uchi" (custom-made swords), each forged with meticulous care, and were mass-produced in production centers such as Bizen Osafune and Mino Seki. This article explores the background and actual conditions of these kazuuchi swords, as well as their impact on sword history, through historical sources.

The Ōnin War and the Explosion of Sword Demand—From Muromachi to Sengoku

The Ōnin War, which broke out in 1467 (Ōnin 1), was a major uprising that reduced Kyoto to scorched earth for eleven years, and at the same time marked a turning point that greatly transformed the history of Japanese swords. Until then, sword demand centered on formal weapons carried by samurai and prestigious swords made for donation to temples and shrines, and sword makers pursued meticulous work by a small elite corps. However, following the Ōnin War, the successive centuries of warfare that continued into the Sengoku period required practical swords on an unprecedented scale.

When ashigaru (foot soldiers) and jizamurai (local samurai) and other lower-ranking warriors and soldiers of peasant origin who had previously been unable to carry swords appeared on the battlefield in large numbers, demand for affordable and practical uchigatana surged. Powerful daimyo placed massive orders with production centers to equip tens of thousands of troops under their command, forcing sword makers to shift to a production system that prioritized quantity over quality.

The Reality of Kazuuchi Swords—The Merits and Demerits of Mass Production

"Kazuuchi" refers to swords produced in large quantities with an emphasis on efficiency, in contrast to the style of master craftsmen who spared no time and skill in crafting each individual sword. The characteristics of kazuuchi swords mass-produced after the Ōnin War are as follows.

• Simplified forging processes: The number of folding-forging cycles was reduced, and examples of forming relatively uniform low-carbon steel directly into sword blades increased. Modern metallurgical analysis confirms that Sengoku-period kazuuchi swords exhibit coarse steel structures indicating fewer forging cycles.
• Uniform shape: The uchigatana form with blade length around 2 shaku 3 sun (approximately 70 cm) became standardized, and workshops established systems for producing identical standard swords in assembly-line fashion.
• Omission or falsification of signatures: Counterfeit blades bearing the names of famous sword makers without authorization and unsigned mass-produced swords flooded the market. Kazuuchi swords bearing the signatures of the Bizen Osafune school were problematic even then as "kazuuchi Osafune" and became a major challenge in later sword authentication.

The "collective signature system" exemplifies this signature problem at Bizen Osafune. The signature of Sukesada, the most popular maker, was reportedly shared by over fifty sword makers belonging to the same workshop, and swords bearing this signature circulated in tens of thousands during the Sengoku period alone. The estimated total production of Osafune as a production center during the Sengoku period reportedly exceeded one million swords, demonstrating the industrial scale of the Japanese sword industry at that time.

However, it would be incorrect to dismiss all kazuuchi swords as inferior. In the workshops of skilled sword makers, swords maintaining minimum quality were produced even while rationalizing the process, and many Sengoku-period kazuuchi swords that receive authentication certificates (preservation or special preservation grade) today are not uncommon.

The Rise of Local Sword Makers—The Dispersal of the Five Schools

Another major change in the Muromachi and Sengoku periods was the dispersal of sword makers, who had been concentrated in the Kinai region and Bizen, to various locations throughout the country. Sengoku daimyo in various regions invited or cultivated sword makers on their own initiative and attempted to establish self-sufficient production systems within their domains.

Mino Province (present-day Seki City area in Gifu Prefecture) is a representative example. Sword makers who had migrated from the late Kamakura period through the period of the Northern and Southern Courts settled in Seki and surrounding areas, and after the Ōnin War rapidly expanded their influence as a group of Mino-school makers. The swords produced by makers such as Kanemoto and Kaneshada, known by the alias "Seki no Magoroku," were favored by Sengoku warlords for their strength and practicality and circulated throughout the country as "Mino-mono."

In Satsuma (Kagoshima Prefecture), the Namihira school maintained a long tradition under the patronage of the Shimazu clan, and in the northeast the Date clan employed sword makers and the tradition of "Sendai-to" was formed.

Bizen and Yamashiro—Fierce Competition Between Two Major Production Centers

Throughout the Muromachi period, the two major forces in sword production were the Osafune school of Bizen Province (present-day area around Setouchi City in Okayama Prefecture) and sword makers in the tradition of the Awataguchirai school of Yamashiro Province (Kyoto Prefecture).

Bizen Osafune had been the largest sword production center since the Kamakura period, and during the Muromachi period it is said that a single school alone had dozens to over one hundred sword makers concentrated there. A highly organized production system was established, including procurement of raw materials, sharing of forge tools, and development of sales networks, and "Bizen-mono" enjoyed the highest reputation with active export both domestically and internationally.

The market price of kazuuchi swords ranged from a few hundred mon to a few kan, which in modern value approximately corresponds to 80,000 to 300,000 yen. This affordability—a fraction of the cost of custom-made swords by master makers—was the economic foundation that enabled their adoption across a broad range of classes from ashigaru to jizamurai. Moreover, in the Mino production area, demand was strong not only for uchigatana but also for polearms such as spears and naginata, and Seki makers established a firm position in the production of polearms as well.

Meanwhile, sword makers in Yamashiro served as official sword makers for the Muromachi shogunate, supplying high-quality custom swords called "josaku" to the shogunal family and powerful daimyo. Though small in number, each blade was of high completion, and "Yamashiro-mono" continues to receive high praise from sword collectors today.

However, after the Ōnin War, when Kyoto became a battlefield and Yamashiro workshops received devastating damage, Bizen's overwhelming mass production capability dominated the Sengoku market. The sword industry of the Sengoku period was an era of conflict between quality and quantity.

What Sengoku Warlords Sought in Swords—Between Utility and Art

What Sengoku warlords sought in swords was not uniform. For warlords who prioritized actual combat, a sword had to be unbreakable, unbendable, and sharp—absolute requirements. Even sword collectors such as Oda Nobunaga and Tokugawa Ieyasu are said to have clearly distinguished between practical combat swords and prestigious blades for appreciation.

The value assessment of swords emphasized grading based on cutting ability: "wazamono," "oo-wazamono," and "saijo oo-wazamono." Yamada Asaemon's "Kaihokensjaku" (published in 1797, Kansei 9) systematized this, but the culture of cutting ability evaluation that preceded it was formed during the Sengoku period.

Aesthetic value came to be emphasized again from the Azuchi-Momoyama period (late 16th century) onward, after the unification of the realm. When Toyotomi Hideyoshi launched a famous sword collection movement called "meibutsu-gari" and exchanges of prestigious blades among daimyo became frequent, swords once again became recognized primarily as prestige goods and works of art.

The kazuuchi swords born from Muromachi's warfare could be said to be the "shadow history" of Japanese swords, yet without them the renowned blades wielded by rulers would never have shone so brightly. The tension between mass production and artistic pursuit is what created the richness of Japanese sword culture—its legacy is quietly inscribed in each sword handled by TOUKENZA today.