Ninja Throwing Disks (senban): Different Types and Their Tactical Uses

Historical Context: The Shinobi’s Silent Weapon

The senban (also romanized as senbon or senban shuriken) emerged during the tumultuous Sengoku period (15th–17th centuries), when Japan was fractured by near‑constant civil war. Ninjas, or shinobi, were specialists in irregular warfare, espionage, and sabotage. They required weapons that were unobtrusive, easy to conceal, and adaptable to many scenarios. The disk‑shaped senban met these needs perfectly. While the star‑shaped hira shuriken is more famous in popular culture, the circular senban was often easier to carry in large numbers and could be thrown with a simpler, more natural wrist motion.

These throwing disks were typically forged from iron or steel, though some Edo‑period examples used brass or copper cores with iron edges. The manufacturing process was straightforward: a circular plate was hammered thin, then quenched and tempered to achieve a balance between hardness (for penetration) and toughness (to avoid shattering on impact). Many historical senban show file marks or grinding marks, indicating they were made by skilled metalworkers who also produced other ninja tools such as shikomi‑zue (hidden weapons in canes) or kaginawa (grappling hooks).

Unlike the ornate swords of the samurai, senban were purely utilitarian. A ninja might carry a pouch with a dozen or more disks, each measuring between 5 and 15 centimeters in diameter. The flat profile allowed them to be stacked or slipped into a belt or the folds of a kimono without creating noticeable bulges. This made them ideal for silent, surprise attacks. The Bansenshukai, a 17th‑century ninja manual, lists senban among the essential tools of a shinobi’s kit, alongside kunai, shuriken, and metsubushi (blinding powders).

Types of Senban: Variations in Design and Purpose

Historically, no single “standard” senban existed. Regional schools of ninjutsu developed their own preferred shapes and sizes. Martial arts researchers and historians have categorized senban into several main types, each optimized for different tactical roles.

Standard Senban (Round, Thin)

The most widespread variant is a simple, flat circle of steel, often with a slight central dimple or a small hole. The rim is usually left sharp, though some examples have a dull edge for practice. These disks weigh between 50 and 150 grams, depending on thickness and diameter. They were thrown with a spinning motion, similar to a modern frisbee, but with much greater speed and precision. The flat surface allowed them to slice through the air with minimal drag.

Tactical Use: Standard senban were used for disabling guards at a distance, cutting ropes or harnesses, and creating distracting sounds when they struck hard surfaces. In close combat, the sharp edge could be used for slashing, or the disk held for a palm‑heel strike by gripping it between thumb and forefinger and punching with the metal edge.

Weighted Senban (Thickened Rim or Core)

Some senban were deliberately made heavier by adding material to the outer rim or by forging a thicker profile. These weighted disks could weigh up to 300 grams. The extra mass increased kinetic energy upon impact, making them capable of penetrating light armor or inflicting blunt‑force trauma even if the edge did not cut. Some weighted senban had a small central hole to which a cord could be attached, allowing the ninja to retrieve the disk after throwing—a feature shared with the chigiriki chain weapon.

Tactical Use: Weighted senban were ideal for breaking bones, stunning opponents, or damaging fragile equipment (e.g., lanterns, pottery). They could also serve as improvised bludgeons if the ninja lost his primary weapon. The added mass made them less aerodynamic over long distances, so they were typically employed at close to medium range (5–15 meters).

Decorative Senban (Intricate Patterns)

Some senban were crafted with engraved designs, clan symbols, or even painted with bright colors. These were not primarily intended for combat but served psychological and signaling purposes. A ninja might throw a brightly painted disk to draw an enemy’s gaze away from his approach, or use a disk with a specific symbol to send a covert message to an ally (e.g., “retreat” or “enemy sighted”).

Tactical Use: Decorative senban worked as distraction devices, much like a flash‑bang or smoke bomb in modern counter‑terrorism. An enemy seeing a glinting or colorful disk sailing past might instinctively turn his head, creating a split‑second opening. Some accounts suggest that ninjas used these disks to startle horses, as horses can be spooked by sudden flashes of color or movement.

Multi‑Point Senban (Scalloped or Star‑Shaped Variations)

Though the pure disk is the classic form, some senban had scalloped edges or multiple points—a cross between a disk and a shuriken. These hybrid designs combined the aerodynamic stability of a disk with the cutting potential of multiple blades. They were harder to manufacture but could cause more grievous wounds.

Tactical Use: These were reserved for assassination and ambush, where maximum tissue damage was desired. The multiple edges increased the chance of severing blood vessels or tendons, making them effective even against armored targets (the points could sometimes find gaps in armor).

Training Senban (Blunt or Wooden)

Practice sessions required lighter, safer versions. Training senban were often made of wood, hardened leather, or dulled metal. They weighed less (20–50 grams) and had a slightly larger diameter to simulate the handling of a live disk without risk of serious injury. Some schools used bamboo rings that could be thrown for accuracy drills.

Tactical Use: Training senban were never used in combat; they allowed the shinobi to develop muscle memory and aim without damaging the sharp edges of their real weapons. Modern practitioners often start with these before moving to steel disks.

Materials and Manufacturing: The Ninja’s Forge

Creating a functional senban required careful selection of materials and heat treatment. Most historical senban were made from tamahagane (the same high‑carbon steel used for samurai swords) or lower‑grade wrought iron. The steel was forge‑welded, then hammered into a thin plate. After shaping, the disk was heated and quenched in water or oil to harden the edge, though many senban were left in a soft state (annealed) to prevent brittleness—a throwing weapon that shatters on impact is useless.

Some senban were treated with a kurogane finish—a rust‑resistant patina that gave the metal a dark, non‑reflective surface. This was essential for stealth operations at night. Brass and copper were occasionally used for their corrosion resistance, but they lacked the cutting power of steel. For more on traditional Japanese metalworking, see the Metropolitan Museum of Art’s Japanese Arms and Armor collection.

Modern reproductions often use stainless steel, which is easier to maintain but historically inaccurate. For collectors, a carbon‑steel senban with visible forging marks and a natural patina is far more desirable. Some craftsmen still produce senban using traditional methods, and these can be found through specialty dealers.

Throwing Techniques: Precision Over Power

Mastering the senban required extensive practice. Unlike the shuriken, which is thrown with a flick of the wrist and a backspin, the disk senban is thrown with a more pronounced arm movement—much like a baseball pitch or a discus throw. The key is to impart a stable spin so the disk flies edge‑first toward the target. The grip is typically between the thumb and index finger, with the disk resting against the palm. Some schools taught an overhand throw (for a vertical spin) and a sidearm throw (for a horizontal spin), depending on the angle of approach and the target’s position.

Training targets were often made of soft wood or bundled straw, with a painted silhouette of a human. Ninjas would practice from various distances (3, 5, 10, and 15 meters) and from kneeling, standing, or moving positions. The goal was to embed the disk in the target with enough force to wound. A well‑thrown senban could cut into a wooden post to a depth of 2–3 centimeters. Advanced practitioners also practiced irimi (entering throws) where they closed distance after throwing to follow up with a melee attack.

Tactical Uses: From Assassination to Escalation

Ninjas were tacticians above all. The senban played multiple roles in their operations, as illustrated below.

Silent Assassination

The senban’s quiet flight made it ideal for eliminating sentries without raising an alarm. A ninja could throw a disk into a guard’s throat or temple, and the victim would die without a sound. The disk itself would often be left behind—anonymity was a feature, as medieval blacksmiths rarely marked senban with identifiable symbols. In some accounts, ninjas used two disks to strike both sides of a guard’s neck simultaneously for a sure kill.

Creating Diversions

By throwing a senban against a stone wall or roof tile, the ninja could produce a sharp clattering sound that drew guards away from their posts. This was especially effective at night when sounds carried further. Decorative senban with bright paint or reflective surfaces could also be caught in torchlight, creating a visual distraction. Some ninjas carried a bag of senban that they would scatter on the ground to cause pursuers to slip or to create noise as they stepped on the disks.

Signal and Communication

Some accounts suggest ninjas used senban as a form of prearranged signal. A specific angle of throw (e.g., arcing up vs. flat) could indicate “danger ahead” or “safe to proceed.” The disks were also left at rendezvous points as markers. The Bansenshukai describes how shinobi left circular stones or metal disks to mark safe houses. You can read a translation of the Bansenshukai at the Ninpo Center’s historical texts archive.

Close Quarters Combat (CQC)

When thrown weapons became impractical (e.g., in a narrow corridor), a ninja could wield two senban like off‑hand weapons. One disk could be used to parry a blade, while the other slashed at the opponent’s face or hands. The sharp rims allowed for draw cuts, similar to a kunai. Some masters taught a technique called “senban no giri” (disk cutting), where the ninja would spin the disk in his palm and then slash horizontally. Another technique was to hold the disk by the edge and use it as a knuckle duster for punches.

Escalation of Force

A ninja might first throw a lightweight, non‑lethal weighted senban to warn or cripple an opponent, then escalate to sharper disks if the threat persisted. This graduated response allowed the ninja to maintain control without unnecessary bloodshed. Some schools taught using a dull senban to strike pressure points or to break a beam in order to collapse a section of a building.

Environmental Manipulation

Senban were also used to cut lantern ropes, slash the strings of bows, or sever the ties on armor. Thrown at the right angle, a senban could slice through a paper wall (shoji) to allow a ninja to pass unseen, or cut the straps of a saddle to unhorse a rider. These uses show that the senban was not just a weapon but a multi‑purpose tool.

Comparison to Other Throwing Weapons

Senban are often confused with shuriken, but the differences are significant:

Feature	Senban	Shuriken (Hira)
Shape	Circular disk	Multi‑pointed star or cross
Thickness	Uniform, thin	Thicker center with tapering points
Throwing style	Overarm / sidearm spin	Flick release with backspin or no spin
Primary purpose	Cutting and blunt force	Penetration and slicing
Number carried	10–20	20–50

Chinese biao (throwing darts) and European plumbata (weighted darts) serve similar roles, but the disk shape gives the senban a unique combination of aerodynamics and concealability. In terms of terminal ballistics, the senban’s cutting edge can create wide, shallow wounds, while the shuriken’s points can puncture deeper. A skilled user would choose the weapon best suited to the target’s armor and the desired effect.

Training and Mastery: The Path of the Shinobi

A ninja’s training in senban began with static targets and gradually moved to moving targets, multiple throws, and throws from unusual positions (hanging upside down, on horseback, or while running). Some schools emphasized “makiwara” practice (straw targets) to build muscle memory. Repetition was the key; a skilled ninja could hit a man‑sized target eight times out of ten at 10 meters.

Advanced techniques included throwing two disks simultaneously (one in each hand) or throwing a disk to intercept an opponent’s blade. This last technique, “senban no katate”, required exquisite timing. It is said that the legendary ninja Fujibayashi Nagato could throw three senban in rapid succession, each striking the same hand‑sized target. Training also involved developing a “throwing meditation” where the shinobi would calm his mind and visualize the trajectory before releasing.

Modern practitioners in the Bujinkan and Jinenkan systems still incorporate senban training, often using rubber or plastic practice disks before graduating to steel. They study not only the physical throw but the psychological dimension—the distraction, the timing, the choice of target.

Modern Relevance and Collecting

Today, senban are studied by traditional martial artists, historical reenactors, and collectors of ninja weapons. When purchasing a senban for practice, it is essential to choose a properly tempered version—many cheap imports are either too brittle (and shatter) or too soft (and bend). Reputable suppliers include Kult of Athena, which offers museum‑quality reproductions made from 1095 carbon steel. Always check local laws regarding throwing weapons, as some jurisdictions restrict their carry or use.

For those interested in historical artifacts, the British Museum holds a 17th‑century senban in its Japanese collection. Viewing such artifacts gives a tangible sense of the weapon’s size and craftsmanship. Many museums in Japan, such as the Iga‑Ryu Ninja Museum in Mie Prefecture, display original senban alongside detailed explanations of their use.

In pop culture, senban appear in video games like the Ninja Gaiden series and Ghost of Tsushima, often stylized as magic throwing rings. While these portrayals are fictional, they keep the legend of the senban alive for a new generation. Collectors should be aware that modern “fantasy” designs with serrated edges or huge diameters bear little resemblance to historical examples.

Conclusion

The senban is far more than a simple throwing disk; it is a testament to the ingenuity of the shinobi, who turned a humble metal disc into a tool of stealth, psychology, and lethal force. Whether used for silent elimination, diversion, signaling, or close combat, the senban exemplifies the ninja principle of “kankyo ni toku” (adapt to circumstances). By understanding the different types and their tactical roles, we gain insight into the sophisticated weaponcraft of feudal Japan’s most elusive warriors.

To learn more about ninja weaponry and combat strategies, explore the Bansenshukai online version or visit your nearest museum with a Japanese arms collection. The legacy of the senban endures as a reminder that even the simplest design can be extraordinarily effective in the right hands.