Sword Culture in the Insei Period (1086–1185): Cloistered Emperors, Samurai Rising, and the Blades They Treasured

What Was the Insei Period?

"Insei" (院政) refers to a political system in which an emperor who has abdicated continues to hold actual political power as a "retired emperor" (jōkō/hōō). Beginning in 1086 (Ōtoku 3), when Emperor Shirakawa handed the throne to Emperor Horikawa while refusing to relinquish political authority, this system continued for approximately 100 years until the establishment of the Kamakura shogunate in 1185. This era was a period of upheaval marked by three simultaneous transformations: internal strife within the imperial court aristocracy (kuge), the rise of the samurai, and the increasing complexity of the manor system (shōen). It also represents a critical turning point in Japanese sword culture.

Retired Emperor Shirakawa and Sword Collecting

Retired Emperor Shirakawa (r. 1086–1129), the founder of insei rule, was the first retired emperor to attempt to position himself at the apex of aristocratic government by privately controlling military force. He established the "Hokumen no bushi" (northern guards) as the enforcement arm of his retired emperor's court (in-chō), bringing powerful samurai directly under his control.

Retired Emperor Shirakawa had a keen interest in swords, and records indicate he commissioned swordsmiths from across the realm to present him with outstanding tachi. The swords of this era show a gradual transition from the slender, slightly curved forms of the early Heian period. The blades became somewhat longer, and the curve (sori) began to shift toward the center of the blade. Many tachi forged during Shirakawa's insei period rank among the finest examples of "ko-tachi" (ancient tachi), and several dedicated to shrines have survived to the present day.

Retired Emperor Toba and the Reorganization of Samurai Forces

The era of Retired Emperor Toba (r. 1129–1156) witnessed the further integration of samurai forces into the core of insei authority. Toba appointed samurai as "Palace Sword Guards" (katana-ban), institutionalizing armed protection within the imperial court.

From the sword-making perspective, this era saw a surge in demand from eastern Japan samurai (Kantō and Tōhoku regions) for refined tachi. The Osafune region of Bizen (present-day Okayama Prefecture), which would later flourish during the Kamakura period, was already establishing its foundation as a swordsmith collective during the insei period. While Bizen swords of Toba's insei period were still technically developing compared to the later Kamakura masterpieces, the nascent forms of organized production systems are evident in this era.

The Minamoto-Taira Upheaval and Changes in Sword Demand

In the late insei period, three major internal conflicts erupted in succession: the Hōgen Rebellion (1156), the Heiji Rebellion (1159), and the Jishō-Jueii War (1180–1185). These conflicts brought dramatic changes in sword demand.

The Hōgen Rebellion (1156): This conflict, which escalated from a dispute between Retired Emperor Sutoku and Emperor Go-Shirakawa into armed combat, heralded the arrival of an age in which samurai military might would determine court power struggles. Samurai of the Minamoto and Taira clans who fought in the battle commissioned swordsmiths from eastern and western Japan to produce combat-ready tachi, and demand surged dramatically.

The Jishō-Jueii War (Minamoto-Taira War, 1180–1185): This five-year nationwide conflict resulted in massive consumption of swords. Simultaneously, among samurai who took to the battlefield, an intense attachment to possessing renowned blades emerged, and this period became the catalyst for the spreading reputation of master swordsmiths throughout the realm.

Retired Emperor Go-Shirakawa and the Emergence of Swords as Art

Retired Emperor Go-Shirakawa (1127–1192), the last retired emperor of the insei period, navigated complex political circumstances from the late Heian through the early Kamakura eras. Though known for his deep interest in cultural pursuits such as imayō and kemari, he was equally active in collecting and presenting swords.

What is notable about Go-Shirakawa's era is that swords began to be recognized not merely as pure weapons but as "sacred objects possessing aesthetic value." As exemplified by dedications to Itsukushima Shrine (records indicate he presented over a thousand tachi), the practice of offering superior blades to deities became established as a way to demonstrate the virtue of retired emperors and military lords. This laid the foundation for the later "culture of presenting renowned swords."

Morphological Characteristics of Insei-Period Swords

Tachi from the insei period (late 11th to 12th century) exhibit the following morphological characteristics:

Changes in Sori (curve): The characteristic "koshi-zori" (hip curve) of the early Heian period—with the maximum curvature occurring roughly in the lower third of the blade—gradually shifted during the insei period toward a more central curvature. This transitional morphology is prevalent in insei-period examples.

Blade Length Trends: Insei-period swords typically had blade lengths of approximately 2 shaku 4 sun to 2 shaku 8 sun (73–85 cm), representing a transitional stage toward the more impressive long tachi of the Kamakura period.

Jigane and Hamon: The jigane of insei-period swords is predominantly small itame and itame grain patterns, while the hamon typically consists of straight-edge (suguha) forms or small-wave (ko-midare) patterns. The elaborate chōji-midare (clove-blossom) hamon characteristic of later Kamakura blades was a subsequent development; insei-period forging remained predominantly simple in form.

The Legacy of Insei-Period Swords in Japanese Sword History

The insei period marks the first critical transition in which the Japanese sword transformed from a "practical tool of warfare" into "a spiritual symbol and work of art for the samurai." The insei authorities' institutionalization of sword dedication and collection, combined with the samurai's growing consciousness of the blade as "the soul of the warrior," provided the foundation for the golden age of Japanese sword-making that would flourish in the subsequent Kamakura period. It is no exaggeration to say that understanding Japanese sword history of the Kamakura era is impossible without knowledge of the insei period.