* Image is for illustrative purposes only.Ko-Bizen Tomonari
古備前友成
Also known as: Ko-Bizen Tomonari; Ancestor of the Bizen Tradition; Supreme Tachi of the Heian Age
Description
Overview of the Sword
Ko-Bizen Tomonari is a tachi forged by one of the major masters of the Ko-Bizen school during the late Heian period in Bizen Province (modern Okayama Prefecture). Designated a National Treasure and held at the Tokyo National Museum, this blade was created by Tomonari (active in the 11th–12th centuries; dates of birth and death unknown), one of the founding masters of the Ko-Bizen school. The Ko-Bizen school was a collective term for swordsmiths active in Bizen Province from the late Heian through the early Kamakura period, with prominent masters including Kanehira, Norimune, Tomonari, and Masatsune. These smiths established the Bizen tradition—one of the most important traditions in Japanese sword history.
The Ko-Bizen School and the Birth of the Bizen Tradition
The Bizen tradition ranks among the five major sword schools (Yamashiro, Yamato, Bizen, Soshu, and Mino) as the longest-continuing and most prolific. From the Ko-Bizen school's founding through the Kamakura period's Ichimonji and Osafune schools, the Bizen tradition continued unbroken through the Northern and Southern Courts, Muromachi, Azuchi-Momoyama, and Edo periods. Tomonari stands as one of the source masters of this great river of Japanese sword culture—a progenitor to all subsequent Bizen swordsmiths. Ko-Bizen tachi display the refined elegance of late Heian style with both fine grain and refined hamon, maintaining standards that rival later works. Tomonari's swords are particularly renowned for their beautiful grain: the densely packed, uniformly fine ko-itame grain gleams with radiant whiteness, possessing an overwhelming beauty that captivates the eye of all who behold it, even after a thousand years.
Tomonari's Technique and Style
The distinguishing feature of Ko-Bizen Tomonari's tachi lies in its faithful embodiment of the late Heian old-tachi style—deep koshi-zori, high shinogi ridge, sharp and slender monouchi—while realizing the distinctive beauty of Bizen grain at the highest level. The grain features uniformly packed ko-itame that glows with bright radiance, and sometimes displays the straight linear reflection characteristic of Bizen known as "bo-utsurie." The hamon is based on ko-midare, scattered with ko-choji, creating an elegant, classical appearance. The kissaki is a small marumaki, and the nakago bears an inscription in raw, unpolished state reading "Made by Tomonari of Bizen Province." Overall, this blade presents a unique world of beauty where the refined sensibility of Heian court culture and the superior quality of Bizen iron have merged as one, unmatched by works from other regions.
The Tokyo National Museum and the Status of National Treasure
Tomonari's tachi held at the Tokyo National Museum possesses exceptionally high cultural-property value as one of the few reliably signed works from the Heian period. Surviving Heian-period swords are rare; among these, examples with reliable signatures and superior quality are rarer still. Tomonari's tachi has been preserved in remarkably fine condition despite more than a thousand years of age, and its designation as a National Treasure reflects both its state of preservation and artistic merit. At the Tokyo National Museum, Tomonari's tachi is frequently presented as one of the most important works in Heian sword exhibitions, and it is cherished alongside Mikazuki Munekika and Doji Kiri Yasutsunga as one of the supreme treasures of early Japanese sword history.
Bizen Land and Sword Culture
Bizen Province (the eastern portion of modern Okayama Prefecture) has long been known as an ideal region for sword production. The Yoshii and Asahi river basins provided abundant iron sand, high-quality pine charcoal, and plentiful water—all conditions necessary for producing the finest iron. The Bizen tradition, which continued unbroken from Tomonari's era, was made possible only through these natural gifts of the land. The beauty of Tomonari's sword grain is grounded in the blessings of Bizen soil. So highly valued were Bizen swords that an Edo-period appraisal document recorded "Bizen works rank first under heaven"—and Tomonari's tachi, as the first crystal of this thousand-year tradition, embodies this very assessment.
The Form of Heian Tachi—The Poetry of Koshi-Zori
The deep koshi-zori curve displayed by Tomonari's tachi is one of the most characteristic features of Heian-period tachi style. Koshi-zori refers to the form where the waist section near the sword's center of gravity curves most deeply; in the later Kamakura period, this evolved into saki-zori and naka-zori. The deep koshi-zori of Tomonari's era was functionally optimal for delivering downward strikes from horseback, while simultaneously possessing graceful curvilinear beauty—visually striking. This koshi-zori curve echoes the "soft, delicate beauty" described in Heian literature such as the Tale of Genji—the flowing drape of a nobleman's robes—demonstrating how the era's aesthetic sensibility penetrated even into practical tools. When viewing the form of this tachi preserved as a National Treasure at the Tokyo National Museum, one experiences a moment when the air of ancient Heian is reborn in the present.
Legacy and Preservation—Conservation and Public Display at the Tokyo National Museum
As Japan's largest comprehensive museum, the Tokyo National Museum bears the responsibility of managing and displaying Japan's most important cultural properties, including National Treasures and Important Cultural Properties. Tomonari's tachi holds a place among the oldest and most important works in the museum's Japanese sword collection, maintained under special care in controlled temperature and humidity. When displayed, Tomonari's tachi is sometimes included in exhibitions alongside Mikazuki Munekika and Doji Kiri Yasutsunga, drawing many visitors as one of the supreme treasures of Heian sword culture. Modern scientific investigation has reconfirmed both the superior quality of Tomonari's grain and the precision of his forging technique, demonstrating that Heian-period swordsmiths achieved work that meets the highest modern technical standards.
Legends & Stories
Ko-Bizen Tomonari is not merely a great sword — it is the beginning of a story. The Bizen tradition that Tomonari helped found would go on to produce the Ichimonji school, the Osafune masters (Mitsutada, Nagamitsu, Kagemitsu, Kanemitsu), and the long unbroken line of Bizen smiths that extends to the present day — the most sustained tradition of excellence in the history of any craft in any culture. The 'ko' (old/ancient) in 'Ko-Bizen' carries the Japanese evaluation that in origin is the truest expression of essence: the earliest Bizen blades do not merely predate their successors but represent a purity that all subsequent development both builds on and departs from. Tomonari's tachi, its Heian-era deep koshi-zori and fine ko-itame still glowing after a millennium, is the point where that vast tradition was still simple, unelaborated, true. In the Tokyo National Museum, three National Treasure tachi from the Heian period — Mikazuki Munechika, Dōjigiri Yasutsuna, and Tomonari — form a trinity of Japan's earliest sword genius. Each represents a different school, a different vision of what the blade could be. Together they show that the Japanese sword was, from its very beginning, an art.