The Shichishitō (Seven-Branched Sword) — Isonokami Shrine's Ancient Inscribed Blade and 4th-Century Wa–Baekje Diplomacy

The shichishi-tō (seven-branched sword), an ancient iron sword that has long been transmitted at Isonomaki Shrine (Isonokami Jingū) in Tenri City, Nara Prefecture, is an indispensable ancient iron sword for considering the history of Japanese swords. It was designated a National Treasure in 1953 (Showa 28).

Unique Form and Inscriptions

The shichishi-tō has the following unique characteristics in form and inscription.

• Total length: approximately 74.8 cm
• Form: It has three branch blades on each side of the blade in a stepped arrangement, for a total of six branch blades. Together with the central blade, this creates a distinctive form called "seven-branched" (shichishi).
• Character: It is believed to have been more ceremonial and symbolic in nature than intended for actual combat.
• Inscription: Approximately 60 or more characters executed in gold inlay (kinkogane) on both sides of the blade.

Since the Meiji period, researchers have made progress in reading the inscription, but some portions remain difficult to decipher due to corrosion, and various theories still exist regarding the identification and interpretation of the characters.

What the Inscription Reveals About Wa and Baekje

According to a leading interpretation of the inscription, the sword is believed to have been made and given by the heir (successor) of the King of Baekje for the King of Wa in the year "Tae□-4" (where □ represents an unclear character). A leading theory interprets "Taiwa" as a borrowed use of the Eastern Jin era name "Taihe" (366–371 CE), which would suggest the sword was made in the late 4th century, roughly around 369 CE. However, alternative views exist regarding the identification of the era name, and no definitive conclusion has been reached.

The context of the gift from Baekje to Wa is valued as a rare written historical source illustrating the diplomatic relations between the Korean Peninsula and Wa (Yamato polity) in the 4th century. Together with the "Monument of the Gwanggaeto the Great King" (also known as the Hotae King Monument), which also records 4th century East Asia, it serves as a precious clue for understanding this era, for which written sources are scarce.

Relationship with Records in the Nihon Shoki

In the entry for the 52nd year of the regency of Empress Jingū in the "Nihon Shoki" (Chronicles of Japan), there is a record stating that an envoy from Baekje presented "the seven-branched sword (nanatsusaya no tachi)" and other items. The view that the shichishi-tō of Isonomaki Shrine is related to the sword mentioned in this record has long been influential, and research comparing the inscriptions on the blade with the written accounts has been conducted repeatedly.

The case of examining a single object through both contemporary written sources—specifically an inscription—and later compiled literature is extremely rare in the history of ancient Japan. However, careful examination is required regarding the correspondence between the dates in the "Nihon Shoki" and actual chronology, and the debate continues as to whether the sword mentioned in the record can be identified with the extant shichishi-tō. The very fact that no definitive conclusion has been reached may itself be said to demonstrate the depth of the research history surrounding this sword.

Isonomaki Shrine as the Place of Transmission

Isonomaki Shrine is an ancient shrine located in Tenri City, Nara Prefecture, and according to tradition, it was deeply involved in the management of weapons by the imperial court in antiquity. The fact that an ancient iron sword was transmitted as a sacred treasure at a shrine dedicated to the deity of martial affairs suggests that swords were long intimately connected with religious belief.

The inscription on the shichishi-tō became widely known when the characters of the gold inlay were identified beneath the rust on the blade during the Meiji period, and this discovery became the starting point for subsequent research on the inscription. There are scarcely any other examples of an iron sword so ancient preserved as a transmitted heirloom maintained above ground rather than as an artifact excavated from the earth, and the existence of the shrine as the place of transmission is inseparable from the value of the shichishi-tō.

The Technique of Gold Inlay

The gold inlay technique used for the inscription involves carving grooves in the shape of characters into the iron surface with a chisel, then hammering gold wire into those grooves to secure it. Unlike ink writing on the surface, because it involves physically combining two metals, the characters can be preserved for more than a thousand years if adhesion to the base metal is maintained.

The fact that the inscription on the shichishi-tō can still be read today is due in large part to both the durability of this technique and the preservation environment provided by careful treatment as a sacred treasure. On the other hand, corrosion caused by rust extends to the inlaid portions as well, so the identification of characters regarding reading remains an ongoing research issue.

Significance in the History of Ancient Sword Craftsmanship

The shichishi-tō transmits to the present day the culture of iron swords from the era when straight swords (chokutō) were used, before the later development of curved Japanese swords (tachi). It has great value in conveying, as an extant physical object, the process by which iron implements and forging techniques flowed into the island through exchange with the continent and Korean Peninsula.

The fact that it has long been preserved as a shrine treasure in the sacred precincts has enabled it to survive in a state where the inscription can still be read even after more than a thousand years. It is a symbolic example demonstrating that ancient swords were treated not merely as weapons but as evidence of diplomacy and objects of religious veneration.

From the Shichishi-tō to the Japanese Sword—Understanding the Era of Straight Swords

The swords of the shichishi-tō era were straight swords (chokutō) without curve, differing from later Japanese swords (kaidō) in both form and the context of their production. The development of curved blades (kaidō) is thought to have occurred around the middle of the Heian period, and the centuries preceding this marked an era in which craftsmen on the islands gradually adopted and assimilated the forging techniques that flowed in from the continent and Korean Peninsula. When one examines straight swords excavated from burial mounds and the treasures of the Shōsō-in repository that transmit knowledge of Nara-period swords alongside one another in chronological order, the flow of pre-history before the establishment of the Japanese sword becomes easier to grasp. Positioned at the earliest stage of this development, the shichishi-tō, as an extant object accompanied by written information in the form of an inscription, continues to be widely referenced from textbooks to specialized research.

Deepening Your Understanding

Because opportunities to see the shichishi-tō in person are limited, the realistic starting point is to become familiar with its distinctive form and inscriptions through photographs and transcriptions of inscriptions found in catalogs and scholarly works. While the appreciation of ancient swords differs in context from Japanese swords of the medieval period and later, possessing a broad perspective on "where iron swords came from and how they developed into Japanese swords" becomes the foundation for understanding swords regardless of era.

For those interested in the origins of the Japanese sword and the history of ancient swords, we invite you to view TOUKENZA's sword catalog and columns, where you can examine both the form and historical context of swords in each era.