Swords of the Tensho Era: Late Koto Period Innovation Before the Shinto Age

Tenshō Era—A Turning Point in Japanese Sword History

The Tenshō era (1573–1593) was one of the most turbulent periods in Japanese history and represents a crucial branching point in the history of Japanese swords. This 20-year span is positioned as a "transitional period" where the end of the koto (old sword) era and the opening of the shintō (new sword) era overlapped, marking a time when the forms, manufacturing methods, and distribution of swords underwent dramatic transformation.

The koto era refers to the period of sword production from the late Heian period through the late Muromachi period. The period from the Keichō era (1596–) onward is called the shintō era, while the Tenshō period falls in the gap between them—corresponding to the "late koto period." The swords of this era possessed the pure aesthetics of koto swords while bearing distinctive characteristics pulled along by the pragmatism of the Sengoku period.

Tenshō-Period Sword Forms—How the Reality of Warfare Changed Blade Design

An essential element when discussing Tenshō-era swords is the transformation in combat styles. Symbolized by the Battle of Nagashino (1575) and the massive introduction of firearms, armor's defensive capabilities came to be valued more highly. As a result, the primary use of swords shifted from "stabbing and striking armored warriors" toward "mobile slashing in close-quarters combat."

The uchigatana produced during this era showed a tendency for blade length to shorten compared to the long blades of the mid-Muromachi period. The difference between the width at the hilt and the width at the point diminished, and the shape evolved from the gentle curvature characteristic of the koto form toward shapes with a thick root and higher point-ward weight distribution. This can be interpreted as a response to the declining frequency of mounted combat and the rise of on-foot (kachi) warfare as the dominant style.

Furthermore, the Tenshō era was also a time when mass-produced swords called kazuuchi flooded the market. Due to Hideyoshi's large-scale military campaigns (such as the Great Return from Chūgoku in the 10th year of Tenshō) and nationwide unification warfare, vast quantities of practical swords were needed. These were manufactured as standardized mass-production blades, distinct from the carefully finished commissioned works produced by individual smiths.

Oda Nobunaga and Toyotomi Hideyoshi's Sword Policies and the Reorganization of Swordsmiths

The establishment of the Oda-Toyotomi regime had direct consequences for the sword industry. Oda Nobunaga is known as a daimyo who actively utilized sword-gifting diplomacy. By presenting renowned swords to his retainers and allies, Nobunaga demonstrated loyalty and hierarchy through "sword diplomacy," which elevated the political value of famous swords and increased commissions to renowned sword smiths. The concept of "meibotsu" (named masterpieces) was formalized during this period, and the records of famous swords lost in the Honnō-ji Incident (1582)—such as the Fudō Yukimitsu—influenced later sword evaluation.

Toyotomi Hideyoshi issued the "Sword Hunt Edict" in the 16th year of Tenshō (1588). This policy confiscated weapons from farmers and temples, restricting sword ownership to the samurai class. While the vast quantities of swords confiscated through the Sword Hunt were ultimately said to be used in the construction of the Great Buddha at Hōkoku-ji Temple in Kyoto, the order also brought changes to sword smiths' workload. As demand from rural areas declined, there was a growing concentration on high-quality commissioned work for samurai and daimyo.

Major Swordsmiths of the Tenshō Era—The Final Brilliance of the Koto Period

From the Tenshō era through the early Keichō period, several notable swordsmiths stood out as the final generation of the koto tradition. Most prominent among them is Horikawa Kunihiro, also called "the founder of shintō swords." A native of Satsuma who began his work during the Tenshō era, Kunihiro later relocated to Horikawa in Kyoto to establish his own school. He is regarded as the "symbol of the transitional period" for creating new forms while inheriting the techniques of the koto masters.

In Bizen's Osafune, swordsmiths who were predecessors of Yokoyama Sukesada continued their activities, preserving the Bizen tradition. However, in the 18th year of Tenshō (1590), a catastrophic flood devastated the Osafune district, destroying the historic settlement of Bizen smiths that had continued since the Kamakura period—a tragedy marked as a symbolic event in sword history. In Yamato, swordsmiths like Kanabō Masatsugu carried on the Yamato tradition, but the turmoil of the Sengoku period weakened connections with temples and shrines, causing the traditional patronage foundation of Yamato metalworking to begin to crumble.

Appreciation Points for Tenshō-Period Swords—Understanding the Gap Between Koto and Shintō

When appreciating and appraising Tenshō-era swords, there are several points worth noting. First is the form of the nakago. When an "ubu nakago" (unaltered tang)—characteristic of the koto period—remains, it indicates the sword has retained its original state. However, many Tenshō-period blades underwent major regrinding (ōsuriage) in later periods.

Regarding the hamon, Bizen-tradition swords may retain gentle choji midare patterns, but the practical orientation of the age shows an increase in suguha and noare blade patterns. The jigane is predominantly itame texture characteristic of the late koto period, though the precision of forging was beginning to decline, and mass-produced pieces sometimes show rough, disorganized grain.

Tenshō-period swords possess a "beauty of contradiction" where koto aesthetics and shintō pragmatism intersect. This era showed the greatest quality disparity between masterworks and mass-produced kazuuchi blades, and understanding this gap becomes key to deeply appreciating Tenshō swords.

Bridge to the Shintō Era—Continuity into the Keichō Period

Marking the threshold of the Tenshō era, the world of Japanese swords entered a new phase. Following the Battle of Sekigahara in the 5th year of Keichō (1600) and the establishment of the Tokugawa shogunate, an age of peace arrived, and swords transitioned from "tools of warfare" to "spiritual symbols of the samurai."

Yet the innovations attempted by Tenshō-period swordsmiths—the rationalization of forms, the reorganization of production centers, and the broadening of distribution networks—were faithfully passed on to the next generation. The new aesthetic sensibilities established by Horikawa Kunihiro influenced numerous swordsmiths of the early Edo period. The scattering of swordsmiths from the Osafune recovery process who then worked throughout the country brought about geographic dispersal of sword culture.

Rather than viewing the Tenshō era solely as "the end of koto swords," reinterpreting it as the "beginning of an age" when Japanese sword culture became nationalized and diversified reveals this turbulent era's swords in far richer meaning.