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

The Insei Period: What Kind of Era Was It?

"Insei" (retired emperor governance) refers to a political system in which an emperor, after abdicating and becoming an "in" (retired emperor) or "houin" (Buddhist retired emperor), continued to hold real political power. It began in 1086 (Oe 3rd year) when Emperor Shirakawa abdicated in favor of Emperor Horikawa but refused to relinquish political power, continuing for approximately 100 years until the establishment of the Kamakura shogunate in 1185. This era saw three simultaneous transformations: internal strife within the court nobility government, the rise of the warrior class, and the increasing complexity of the manor system, making it a turbulent period and an important turning point in sword culture as well.

This system, which displaced regency politics and had the retired emperor personally lead government affairs, was characterized by the suppressed influence of the Fujiwara clan, who were the emperor's maternal relatives, and the retired emperor's decision-making through the "inkcho" (retired emperor's administrative office), an institution under his direct control. During the insei period, land donations (manors) became concentrated under the retired emperor, and from the necessity of managing and defending these manors as an economic base, systems for the organized mobilization of warriors were established. In this process, swords came to play an important role not merely as weapons, but also as gifts demonstrating loyalty to the retired emperor and powerful nobles.

Emperor Shirakawa and Sword Collection

Emperor Shirakawa (insei 1086-1129), the founder of the insei system, was the first retired emperor to attempt to stand at the apex of court government by maintaining military force under his private control. He established the "Hokumen no bushi" (Northern Palace guards) as the effective military force of the retired emperor's office and brought powerful warriors directly under his command.

There are records indicating that Emperor Shirakawa held a keen interest in swords and requested skilled sword makers from various provinces to present fine tachi (long swords) to him. The swords of this era showed a transitional form, departing somewhat from the slender, low-curved shape of the early Heian period, with slightly longer blade lengths and curvature gradually shifting toward the center. Many of the tachi produced during Emperor Shirakawa's insei are of superior quality among "kotachi" (old tachi), and extant examples have been confirmed as swords presented to shrines.

The Hokumen no bushi supposedly took their name from their headquarters on the north side of the retired emperor's palace, and it was a system that allowed warriors of low status to gain opportunities to serve in close proximity to the retired emperor. Through this system, warriors who had previously been positioned at the periphery of aristocratic society gained experience in places close to the political center, laying the groundwork for the later rise of the warrior class. Most of the tachi presented before Emperor Shirakawa are believed to have been made with an eye toward presentation to shrines and temples or use in ritual contexts rather than actual combat, and many are said to have been carefully crafted with considerable attention paid to the finish of the hamon and jihada.

Emperor Toba and the Reorganization of Warrior Groups

The era of Emperor Toba (insei 1129-1156) was a period in which the process of integrating warrior groups into the center of insei power advanced further. Emperor Toba positioned warriors as "kataana-ban" (palace sword guards), institutionalizing armed security within the court.

From the perspective of swords, it is noteworthy that during this era demand increased among warriors in the eastern regions (Kanto and Tohoku) for refined tachi. The Osafune region of Bizen (present-day Okayama Prefecture), prior to its flourishing in the Kamakura period, was establishing the foundations of its sword-maker communities beginning in this insei period. While Bizen swords of Emperor Toba's insei era were still technically in a developmental stage compared to later Kamakura masterworks, the beginnings of an organized production system can be seen in this period.

During Emperor Toba's era, warriors managing manors accumulated independent military strength in the provinces, and correspondingly, sword-maker groups throughout the land developed their techniques by responding to orders from local warriors. In regions like Bizen, blessed with high-quality iron sand and fuel, examples emerged of sword makers inheriting techniques on a family basis, with entire settlements establishing systems of specialized labor division. The spread of such production systems signified a transition from a stage where individual master craftsmen produced tachi one at a time to a stage where production centers capable of consistently supplying swords of a certain standard were being formed.

The Minamoto-Taira Upheaval and Changes in Sword Demand

In the late insei period, three major internal conflicts occurred in succession: the Hogen Rebellion (1156), the Heiji Rebellion (1159), and the Jisho-Juei Wars (1180-1185). These conflicts brought dramatic changes in demand for swords.

• Hogen Rebellion (1156): This conflict, in which the confrontation between Emperor Sutoku and Emperor Go-Shirakawa escalated into armed violence, announced the arrival of an era in which the military power of warriors determined political struggles among the imperial family and court nobility. Minamoto and Taira warriors who participated in the battle commissioned combat-ready tachi from sword makers in the eastern and western regions, and demand surged dramatically.
• Jisho-Juei Wars (Minamoto-Taira Wars, 1180-1185): This nationwide civil war lasting five years brought about massive consumption of swords. On the other hand, among warriors heading to the battlefield, a strong attachment to possessing famous blades was born, and this also became an opportunity for the reputations of skilled sword makers to spread throughout the nation.

Through this series of internal conflicts, swords shifted their emphasis from ritual instruments of the nobility to practical tools of warriors. As the outcome of battles remained directly linked to sword practicality, warriors came to place emphasis on cutting edge and durability, and sword makers are believed to have been increasingly required to produce blades suited for actual combat. With the end of the Jisho-Juei Wars and the establishment of a warrior government in Kamakura, the center of sword demand gradually shifted eastward, and the techniques and networks cultivated during the insei period were carried forward into the sword culture of the Kamakura era.

Emperor Go-Shirakawa and the Emergence of Artistic Value in Swords

Emperor Go-Shirakawa (1127-1192), the last retired emperor of the insei period, survived complex political circumstances spanning the late Heian through early Kamakura periods. He is known for his deep interest in cultural pursuits such as imayo (popular songs) and kemari (kickball), and was also actively engaged in collecting and presenting swords.

What is noteworthy about Emperor Go-Shirakawa's era is that swords began to be recognized not merely as pure weapons but as "sacred objects possessing artistic value." Exemplified by large-scale sword presentations to Itsukushima Shrine (particularly those by Taira Kiyomori and others), presenting superior tachi to shrines and temples became established as an act demonstrating the virtue of retired emperors and military commanders. This formed the foundation for the later "culture of presenting famous swords."

Emperor Go-Shirakawa was a rare figure who experienced all three major upheavals—the Hogen Rebellion, Heiji Rebellion, and Jisho-Juei Wars—and his reign was marked by complex political maneuvering. Despite such turbulence, the retired emperor maintained devout faith in temples and shrines and continued to make presentations, attempting to make his authority and virtue visible through donations of treasures including swords. The preservation of the culture of treating swords as offerings to shrines and temples even in an era when warrior power determined politics held important significance for the subsequent development of Japanese swords as objects possessing both the character of weapons and that of art objects.

Morphological Characteristics of Insei-Period Swords

The following morphological characteristics are seen in tachi of the insei period (late 11th to 12th centuries).

• Changes in curvature (sori): Many insei-period tachi exhibit a transitional form in which the position of curvature gradually shifts toward the center, departing from the early Heian "kosuzori" (low curve)—a form in which the highest point of the curve is located near the lower third of the blade length.
• Blade length tendency: Most insei-period swords have blade lengths of approximately 2 shaku 4 sun to 2 shaku 8 sun (73-85 cm), representing a transitional stage preparing for the grand, long tachi of the Kamakura period.
• Jihada and hamon: The jihada of insei-period swords is primarily koitame and itame, and the hamon is typically suguha (straight edge) or ko-midare (small irregular patterns). The ornate choji-midare (clove-leaf pattern) hamon is a development of the mid-Kamakura period and later; the insei period was still dominated by simple forms.

Additionally, the nakago of tachi from this period is relatively long, and it is believed that the tsuka was made long to facilitate single-handed operation by mounted warriors from horseback. Few sword makers signed their work with mei, and most extant insei-period tachi have come down to us unsigned (mumei), with dating determined comprehensively based on the characteristics of the jihada, hamon, and overall form.

Perspectives on Appreciating Insei-Period Tachi

The number of extant insei-period tachi is limited, and most consist of pieces that came down to us as presentations to temples and shrines or that have been carefully preserved through subsequent eras. Since dating is determined not only from the mei but from comprehensive elements such as form, jihada, and hamon, carefully comparing these aspects during appreciation helps deepen understanding. It is also important to note that many examples have undergone resharpening or suriage (polishing to shorten the blade) in the course of their long transmission, so the original form may not be entirely preserved. For determining the date and authenticity of swords, confirmation through certificates issued by specialized institutions is the surest method, and evaluation in conjunction with documented provenance is desirable.

What Insei-Period Swords Left in the History of Japanese Swords

The insei period was the first turning point at which the Japanese sword transformed from "practical battlefield equipment" to "spiritual symbol and art object of the warrior class." The accumulation during this era, in which insei power institutionalized sword presentation and collection, and warriors came to regard swords as "the soul of the warrior house," formed the foundation for the subsequent golden age of Japanese swords in the Kamakura period. It is not an overstatement to say that one cannot discuss Kamakura masterworks without understanding the insei period.