The Balance of Fumbaari and Kissaki Width: The Philosophy of Center-of-Gravity Design Differing Between Combat and Display Use

Fumbaari—The "Philosophy of Width" in Japanese Swords

Looking at a Japanese sword's blade from the side, one notices the width differs between the area near the blade base (hamoto) and the area near the point (kissaki). This characteristic—where the width near the blade base (motohaba) is broader than the width near the kissaki (sakihaba)—is called "fumbaari."

The degree of fumbaari—that is, the ratio of motohaba to sakihaba—is a critical design parameter that fundamentally determines the sword's center of gravity position, operability, and visual impression. This article examines the relationship between fumbaari and sakihaba from functional, aesthetic, and historical perspectives.

Defining Base Width, Kissaki Width, and Fumbaari

Base Width (motohaba): The blade width directly above the habaki crossguard. This is the width where the habaki contacts the blade, nearly equal to the blade's maximum width.

Kissaki Width (sakihaba): The horizontal width of the point (the width from the yokote line to the tip's edge).

Fumbaari (踏張り): A concept expressing the ratio of sakihaba to motohaba. When the sakihaba is small relative to motohaba, the sword is said to have "large fumbaari" (pronounced taper), and when sakihaba approaches motohaba, it is said to have "small fumbaari" (weight concentrated at the point).

Expressed numerically:

• Large fumbaari (combat-oriented tendency): sakihaba/motohaba ≤ 0.5–0.6
• Small fumbaari (viewing/Nanbokucho-style): sakihaba/motohaba = 0.7–0.9

The Relationship Between Fumbaari and Center of Gravity

Fumbaari directly determines the sword's center of gravity position.

Large Fumbaari (Tapered Type)

Small sakihaba = light at the point → center of gravity positioned near the handle (tsuka), closer to the hand.

Impact on operability:

• Hand-end center of gravity enables swift manipulation and directional changes
• The sword becomes "easier to rotate"
• Less fatigue during extended holding

Impact on cutting power:

• The light point produces less momentum than point-heavy designs
• However, combined with the biomechanics of pulling cuts, sufficient cutting power is still achieved

Small Fumbaari (Point-Heavy Type)

Sakihaba close to motohaba = heavy at the point → center of gravity shifts toward the point.

Impact on operability:

• Distant center of gravity makes rapid directional changes difficult
• Each swing generates greater cutting power and centrifugal force
• Extended holding causes accumulated fatigue

Impact on cutting power:

• Large centrifugal force during overhead strikes favors heavy cutting
• Well-suited to mounted overhead-striking attacks

Era-by-Era Changes in Kissaki Width—History Reveals the Evolution of Design Philosophy

The ratio of motohaba to sakihaba in Japanese swords changes across eras, and these changes closely track transformations in combat style.

Kamakura Period—The Golden Age of Fumbaari

Kamakura period (12th–14th century) tachi are characterized by "large fumbaari" (pronounced taper).

Typical Kamakura tachi ratio: motohaba 3.2 cm, sakihaba 1.6 cm (sakihaba/motohaba = 0.5)

In the mounted warfare of this era, sword maneuverability was paramount. Positioning the center of gravity closer to the hand enabled quick directional changes and diverse cutting techniques. The combination of "koshizori" (deep curve near the hilt) and fumbaari formed the functional-aesthetic foundation of Kamakura tachi.

Nanbokucho Period—Ootatachi and the "Expansion of Kissaki Width"

The ootatachi and nodachi that became popular in the Nanbokucho period (14th century) tended to have relatively wider kissaki.

Demand for powerful "goujou" (imposing swords) drove kissaki expansion, and blades with "large kissaki" became increasingly common. This trend reflected the era's aesthetic values, emphasizing "visual intimidation" and "overwhelming striking power."

Muromachi–Sengoku Period—Balancing Utility and Aesthetics

Uchigatana from the Muromachi–Sengoku period (15th–16th century) had less pronounced fumbaari than Kamakura tachi, yet better proportions than the imposing Nanbokucho style.

Typical uchigatana ratio: motohaba 3.0 cm, sakihaba 1.8–2.0 cm (sakihaba/motohaba = 0.6–0.67)

This era represents a time when swordsmiths sought equilibrium between practical battlefield functionality and artistic appreciation.

Edo Period—Shift Toward Display Use and Kissaki Width Changes

With the Edo period (17th–19th century) came diminished combat use, and swords became "art objects and symbols of status." Correspondingly, visual "well-balanced proportions" gained priority, and the motohaba-to-sakihaba ratio shifted.

New Sword period (early Edo) characteristics: Kissaki width became slightly broader, with fumbaari less pronounced than the Kamakura period. Swords with a "slender, well-proportioned" appearance were preferred.

New-New Sword period (late Edo) characteristics: Within a movement toward "revival" of ancient blades (Kamakura and Muromachi), some swordsmiths deliberately emphasized fumbaari.

Appreciation Points—Understanding Era and Lineage Through Fumbaari

When appreciating a Japanese sword, examining the motohaba and sakihaba offers clues to its era and smithing lineage:

Application to Modern Swordcraft

When contemporary swordsmiths create a blade, fumbaari is designed according to the customer and intended use:

• Iaido practice: Hand-end center of gravity (large fumbaari) enables easier handling
• Art exhibition: Pursuit of period-appropriate aesthetics through fumbaari design
• Gifts and collectibles: Custom proportions tailored to the customer's preferences

Conclusion—Fumbaari as "The Voice of Its Age"

The ratio of fumbaari and sakihaba is a design language that speaks to the sword's era—its "views on warfare, aesthetics, and social order." The elegant taper born from Kamakura mounted combat, the imposing presence of the Nanbokucho age, the refined beauty nurtured by Edo's peace—each carries the necessity of its time.

The next time you hold a sword, please direct your attention to the motohaba and sakihaba. Within that ratio dwells the philosophy of function and beauty that swordsmiths from centuries past instilled in their blades.