The Golden Age of Blade Patterns in the Nanboku-chō Period: The Greatest Masterpieces of Chōji Midare and Their Influence on Later Generations

The Nanboku-chō Period—Where Upheaval and Artistry Intersect

The Nanboku-chō period (1336–1392) was one of the most turbulent eras in Japanese history, marked by intense political upheaval and military conflict. After the collapse of Emperor Go-Daigo's Kenmu Restoration (1333), an unprecedented situation unfolded in which the Northern Court in Kyoto (backed by the Ashikaga clan) and the Southern Court in Yoshino (allied with Emperor Go-Daigo) coexisted for nearly sixty years.

The explosive surge in military demand during this period caused Japanese sword production to skyrocket. Yet this was far more than mere mass production—it was during this era that the aesthetics of Japanese swordmaking reached one of its zenith. The crowning achievement in blade patterns, known as "Chōji Midare," was born precisely in this turbulent age.

Chōji Midare: What Is It?—A Blade Pattern Likened to Clove Blossoms

"Chōji Midare" is a blade pattern featuring a succession of hardened edges in rounded, bulging shapes resembling clove blossoms. Along the blade's edge line, patterned forms with round "heads" and "feet" at their bases repeat continuously.

Technical Classification of Chōji Midare

Chōji Midare has several morphological variants:

Ko-chōji (Small Clove Pattern): Small, refined clove-shaped forms. These require delicate and precise technique and were a specialty of the Ichimonji school during the Kamakura period.

Ō-chōji (Large Clove Pattern): Large, lavish clove-shaped forms. These reached their peak during the Nanboku-chō period. The boldness of the blade pattern reflects the ferocity of the era.

Kaeru-ko Chōji (Tadpole Clove Pattern): A distinctive variant where the head of the clove pattern becomes elongated like a "tadpole."

Nioi Chōji (Fragrance Clove Pattern): Clove patterns with few particles of nie, centered instead on "nioi" (a subtle, diffuse radiance). Creates a calm and refined impression.

Crafting Difficulties of Chōji Midare

Chōji Midare ranks among the most difficult blade patterns to create in Japanese swordmaking. The reasons are:

1. Precision of Clay Application (Tsuchioki): Creating each clove shape requires extremely fine control over how "yakiba-tsuchi" (hardening clay) is applied to the blade before quenching.

2. Uniform Temperature Control During Quenching: Even slight variations in furnace temperature affect the clove pattern's shape.

3. Water-Quenching Technique: The angle and speed of water quenching subtly alter the clove pattern's form.

Only by perfectly controlling all these factors can a beautiful Chōji Midare be created.

Master Craftsmen and Masterpieces of the Nanboku-chō Period—The Golden Age of Chōji Midare

Master swordsmiths who perfected Chōji Midare during the Nanboku-chō period and their representative works:

Osafune Kanemitsu

A swordsmith from Osafune in Bizen Province and one of the most significant blade-makers of the early Nanboku-chō period (mid-14th century). Kanemitsu's Chōji Midare is characterized by large, bold patterns with a wide hardening zone. Many celebrated examples of Kanemitsu's work survive today, and several are designated as Important Swords or Important Cultural Properties by the NBTHK.

Lineage of Osafune Kagesude and Nagamitsu

The techniques of Nagamitsu (a renowned craftsman of the late Kamakura period) were inherited and developed by his descendants and disciples during the Nanboku-chō period, preserving and advancing Chōji Midare techniques as the Osafune school.

The Fukuoka Ichimonji Lineage

The Ichimonji school was a lineage continuing from the Kamakura period, and Ichimonji blades bearing the signature "Yoshiji" are highly regarded as masterpieces of Chōji Midare. Swordsmiths following the Ichimonji tradition remained active during the Nanboku-chō period.

Formal Characteristics of Nanboku-chō Swords—"Swords from the Era of Enbu and Teiji"

Swords from the Nanboku-chō period possess distinctive forms clearly different from those of the preceding Kamakura period and the subsequent Muromachi period.

Enlargement of Blade Length (Popularity of Ōdatachi and Nodatachi): During the intense outdoor combat of the Nanboku-chō period, longer blades proved advantageous, leading to production of "ōdatachi" (great longswords) and "nodatachi" (field swords) exceeding 3 shaku (approximately 90 cm) in blade length. Many tachi that were later "polished down" (shortened through edge re-profiling) originated in this period.

Wide Blade Width and Robust Form: The blade body is broad with an overall impressive appearance. Characteristically, "the difference between the width at the base and the width at the point is substantial," with the center of gravity closer to the handle.

Shallow Curvature (Reduced Curve): The curve tends to become shallower, reflecting the transition from mounted to foot combat.

Influence on Later Periods—The Lineage of Chōji Midare

The Chōji Midare of the Nanboku-chō period exerted profound influence on Japanese swordmaking techniques in subsequent eras.

Continuation into the Muromachi and Sengoku Periods

Upon entering the Muromachi period (1392–1573), after the Ōnin War (1467) and into the Sengoku period, mass production demands favored the "suguha" (straight blade) and "gunome" patterns, which are easier to create than Chōji Midare. Nevertheless, master craftsmen of Bizen continued producing Chōji Midare.

The "Kodatsu Utsushi" (Copying Ancient Swords) Boom of the Edo Period

During the Edo period (1603–1868), as the movement to "learn from ancient works" gained momentum, Nanboku-chō Chōji Midare became studied as the "ideal model." Master smiths such as Suishinshi Masahide and Taikei Naohata worked to revive the techniques based on famous swords from the Nanboku-chō and Kamakura periods.

The Challenge for Contemporary Swordsmiths

Even today's Living National Treasures and swordsmiths designated as bearers of Important Intangible Cultural Properties approach Chōji Midare as "the most challenging blade pattern." Creating works that surpass Osafune Kanemitsu's large Chōji Midare from the Nanboku-chō period is said to be one of the ultimate goals for contemporary swordsmiths.

Points of Appreciation for Nanboku-chō Swords

Key points collectors and enthusiasts should observe when appreciating Nanboku-chō period swords:

1. Boldness of the Chōji Midare: Large, dynamic clove patterns are characteristic. Those creating a "lively" impression are highly valued.

2. Condition of the Steel Surface (Jigane): The vitality of the itame-nagare (flow-grain) surface. Steel with active jikage is most prized.

3. Shape of the Kissaki (Point): Generous and deeply-set kissaki are characteristic of the Nanboku-chō period. Those with deep "kaeri" (return) are typical.

4. Evidence of Polishing Down: When a ōdatachi has been polished down, understanding the original blade length and morphological changes is important.

Conclusion—The Gift the Nanboku-chō Period Gave to Japanese Sword Aesthetics

The sixty years of the Nanboku-chō period were, in political terms, an era of chaos. Yet from an artistic perspective of blade-smithing, it was a "golden age of blade patterns" in which the highest art form—Chōji Midare—blossomed.

Warfare compelled swordsmiths to produce many swords, through which their techniques were refined and their pursuit of beauty deepened—this is the paradoxical charm of Nanboku-chō swords.