Tsuba of the Nanbokucho and Muromachi Periods: Openwork Flourishes and the Rise of the Shoami School
* Image is for illustrative purposes only.Table of Contents
Civil War and Tsuba—An Explosive Surge in Demand
The Nanboku-chō period (1336–1392) was one of the most tumultuous eras in Japanese history, with the Northern Court led by Ashikaga Takauji and the Southern Court of Emperor Go-Daigo turning the entire nation into a battlefield for more than half a century. The demand for swords among warriors constantly preparing for battle reached unprecedented levels, and the craftsman groups supporting military equipment—sword makers, armor smiths, sword fitting artisans—underwent rapid specialization. Within this flow, the occupation of "tsuba smith (tsuba-shi)" became independent from sword making, and groups of craftsmen specializing in tsuba production emerged in various regions.
Before the Nanboku-chō period, tsuba were predominantly simple iron disks made by punching thick iron plates. However, as warfare intensified, tsuba transcended their function as mere hand guards, transforming into symbols of warrior status and authority, and eventually becoming concrete expressions of faith and aesthetic sensibility. Their shapes diversified from circular forms to mokkō shapes, angular forms, diamond shapes, and irregular ellipses, while both lightness and refinement advanced in tandem.
The Flowering of Sukashi Technique—From "Displaying" Iron to "Piercing" It
The most remarkable technological innovation spanning the Nanboku-chō to Muromachi periods was the full development of sukashi (piercing) technique. Sukashi involves opening decorative holes in the tsuba body, transcending mere weight reduction through material removal to use iron itself as a formal language of expression.
The main sukashi forms are as follows.
| Sukashi Form | Characteristics |
|---|---|
| maru-sukashi (round piercings) | Multiple circular holes arranged regularly or irregularly; one of the oldest forms. Simple yet the diameter and precision of holes reveal the craftsman's skill directly. |
| mokkō-sukashi (wood-melon piercings) | Four-lobed piercings derived from the "mokkō-mon" (wood-melon pattern) in Heian nobility's costume. A courtly design inherited by the warrior class, symbolizing the cultural fusion born from the Nanboku-chō upheaval. |
| kuruma-sukashi (wheel piercings) | Piercings featuring wheel motifs from dharma wheels or ox-carriage wheels. While serving as a symbol of Buddhist cycles and salvation, they possessed versatility appealing to both courtly and military cultures. |
| katana-kata-sukashi (sword-shaped piercings) | Piercings employing the outlines of swords, blades, and cross shapes as the piercing design itself. A design expressing the direct martial spirit of Sengoku warriors concisely. |
Sukashi served not only aesthetic purposes but also functional rationality. If a tsuba was too heavy, the balance of the entire sword would shift toward the hand, reducing manipulability. Weight reduction through sukashi contributed directly to sword balance adjustment—a thoroughly deliberate technical decision.
Forging and Iron Surface—The Material Essence of "Nanboku-chō Tsuba"
In discussing tsuba of this era, the treatment of iron as material cannot be overlooked. Tsuba smiths of the Nanboku-chō to Muromachi periods repeatedly folded and forged domestically-produced iron similar to tamahagane, creating distinctive forged surfaces on the tsuba body.
Particularly noteworthy is the rough forged surface later called "oni-ita tetsu" (demon-plate iron). This surface, intentionally left unsoftened to retain the iron's inherent crude expression, resonates with the wabi-sabi aesthetic pursued in the tea ceremony—the profound beauty dwelling within imperfection. Entirely different from the refined colored-lacquer gold-work tsuba of the Edo period, collectors captivated by this "beauty of rough surfaces" remain numerous even today.
The treatment of the tsuba's perimeter (ear) also changed over time. The Nanboku-chō period saw many tsuba with angular "kado-mi" (angular ears) in cross-section, but by the late Muromachi period, rounded "maru-mi" (round ears) increased, adding tactile comfort and visual softness. Reading such minute changes became an important foundation for dating unsigned tsuba.
The Establishment of the Shōami School—Tsuba Craftsman Groups Spreading Nationwide
From the late Muromachi period through the early Edo period, the group leaving the deepest mark on Japanese tsuba production history was the "Shōami School (Shōami-ha)." "Shōami" was not the surname of a single family but rather a meiseki—a craftsman's name passed down as a title—originating in Kyoto with branch schools forming across the nation in Edo, Nagoya, Kaga (Kanazawa), Sendai, and Hakata.
The Shōami School's greatest achievement was establishing a system capable of supplying high-quality tsuba across a wide range of price points and scales. Upper-tier works were artworks with delicate sukashi and sophisticated iron-surface treatment, while mass-produced items were inexpensive functional military equipment reaching even lower-ranking warriors. The disproportionately high proportion of Shōami-school works among extant tsuba from the Muromachi through Edo periods owes to this system.
The main characteristics of Shōami tsuba are as follows.
- Three-hole structure incorporating a kogai (skewer) hole and kozuka (small sword) hole
- Black rust treatment with a "scorched" appearance achieved through tempering
- Understated and dignified design based on mokkō-sukashi and maru-sukashi
Works that achieved high standards of both dignity and function as "warrior's tools."
Modern Evaluation of Muromachi Tsuba—Museum Collections and Market Value
As of 2026, tsuba from the Nanboku-chō to Muromachi periods are housed as important collections in major museums nationwide, including the Tokyo National Museum, Kyoto National Museum, and Osaka Municipal Museum of Art. Muromachi tsuba designated as Important Cultural Properties or Important Art Objects are known in collecting circles as "a field where discernment is tested" due to dating difficulties.
In the market, the vast majority of Muromachi-period tsuba are "unsigned," with dating determined through consistency of form, forged surface, and sukashi style. A well-preserved Shōami-school mokkō-sukashi tsuba can trade in the hundreds of thousands of yen range, while pieces with daimyo provenance sometimes exceed tens of millions of yen.
Worth noting is the recent revival among young sword collectors of an aesthetic eye appreciating "rough-surfaced iron flavor." Standing apart from the brilliance of Edo gold-work tsuba, the "iron's own narrative" possessed by tsuba of this era continues to occupy a unique position in contemporary collecting culture.
Conclusion—The Aesthetics of Tsuba as Crystallized Sengoku Spirit
Tsuba of the Nanboku-chō, Muromachi, and Sengoku periods were sculptural objects crystallizing the tension of turbulent times and craftsmen's creativity. Through sukashi technique, they transformed "heavy iron" into "delicate design," and through the organizational power of the Shōami School, they disseminated technique nationwide. Without tsuba of this era, neither the subsequent flourishing of Edo gold-work tsuba nor the exuberance of post-Momoyama sword decoration culture would have emerged.
As Japan eventually entered the peaceful Edo period, tsuba transformed in nature from tools of actual combat to the pinnacle of craftsmanship. To understand this turning point, the ability to perceive the Nanboku-chō and Muromachi periods—the "protoplasm of tsuba"—is an indispensable refinement for sword enthusiasts.
