Complete Guide to Wakizashi Construction Variations: Hira-zukuri, Shinogi-zukuri, Kiribe-zukuri, and Unokubi-zukuri

Wakizashi and Construction Methods

Wakizashi (脇差) are swords with blade lengths of 1 shaku to less than 1.8 shaku (approximately 30–55 cm), worn as the smaller blade in a daisho pair alongside a longer sword (uchigata or tachi) by samurai. Because wakizashi exhibit considerable variation in blade length, diverse construction methods have been employed, making the classification of blade shape a crucial aspect of appraisal.

Hirazukuri (Flat Construction)

Hirazukuri is a construction method with a flat cross-section, lacking a shinogi ridge on the blade sides. While most common in tantō, it is also widely used in wakizashi.

Characteristics:

• The hamon can be observed broadly, and the jihada texture is clearly visible
• The blade is lightweight and portable
• A fundamental form widely produced from the Kamakura through Edo periods

Hirazukuri wakizashi often feature longer blade lengths, and examples exceeding 1.5 shaku are sometimes prized as "sunobinaki wakizashi."

Shinogizukuri (Ridged Construction)

Shinogizukuri employs the same standard cross-section as tachi and uchigata, with a shinogi ridge running along the blade sides. This construction is widely adopted in wakizashi as well.

• Provides greater rigidity and strength than hirazukuri, suitable for practical combat use
• When curvature is present, the form approaches that of uchigata, sometimes making distinction from "suntsumari uchigata" difficult
• In Edo-period wakizashi, shinogizukuri became standard

Kiribazukuri (One-Sided Ridge Construction)

Kiribazukuri is a specialized cross-section that retains a flat surface on the mune (spine) side while establishing a shinogi ridge only on the ha (edge) side.

• The blade's edge-side cross-section is wedge-shaped, providing superior cutting penetration
• Primarily seen in large wakizashi and tachi from the Nanboku-Chō through Muromachi periods—a classical form
• Became less common after the Shintō period, though revival examples were created during the late Edo period

Unokubizukuri (Cormorant Neck Construction)

Unokubizukuri features a blade that narrows midway, then widens again toward the kissaki (point). The name derives from its resemblance to a cormorant's neck when viewed from the side.

• A classical form found in tachi and large wakizashi
• The blade's graceful curvature is a key point of appreciation
• Well-executed examples are highly valued

Kanmuri Otoshi Zukuri (Crown Drop Construction)

Kanmuri Otoshi Zukuri is distinguished by a cross-section in which the mune (spine) near the kisaki has been shaved away, designed to improve thrusting capability.

• The blade tip approaches a triangular pyramidal cross-section, increasing penetration
• Common in tantō and wakizashi
• The name "kanmuri otoshi" ("crown drop") references the removed mune profile

Construction Methods and Correspondence to Schools and Smiths

Each construction method typically correlates with specific schools or historical periods:

Construction Method Evaluation in NBTHK Appraisals

In NBTHK examinations (for Hozon, Tokubetsu Hozon, Jūyō Tōken rankings, etc.), whether the construction method aligns with the historical period and school is a critical evaluation standard. For example, a wakizashi attributed to "late Heian Bizen" craftsmanship that exhibits Edo-period shinogizukuri would present a contradiction in period attribution. Construction method serves as the "first impression" in sword appraisal and is always verified.