The shinai (竹刀) is the weapon used in kendo practice. It is composed of four bamboo blades (or synthetic materials such as carbon fiber) held together by leather pieces.
It is used for training because of its flexibility and high resistance to shocks. During katas, it is preferred to the bokken.
The appearance of the shinai probably dates back to around the 17th century. This training weapon was developed in order to allow real assaults during training, which is not possible with the bokken, a full wooden sword.
Combined with the use of the bogu, the use of the shinai allows for training at real speed and with real strikes without the risk of bodily harm to the practitioner.
However, it took several centuries for kenjutsu (the ancestor of modern kendo) training with the shinai to become established in the various sword schools in Japan instead of the traditional training with katas.
Many sword schools gradually recognized that in order to truly understand the essence of combat, it was necessary for fighters to equip themselves with the bogu and use the shinai in order to become familiar with the confusion that results from bold and unrestrained training.
The "classic" shinai (made of bamboo) is composed of four bamboo blades (take) held together by two pieces of leather (deerskin), one at each end, connected by a cord (tsuru).
The end piece (ken-sen) of the shinai represents the tip of the sword and is called saki-gawa. It is attached to the tsuru which, while holding together the take blades that make up the weapon, materializes the part opposite the edge of the sword blade.
The saki-gawa often covers a small plastic piece called saki-gomu which prevents the ends of the bamboo blades from being pinched.
The tsuka-gawa is the leather sleeve that serves as the handle of the shinai.
Between the saki-gawa and the tsuka, a leather cord called naka-yui or nakajime ensures the maintenance of the blades. It is usually located at the first third of the length of the shinai.
The tension of the tsuru is ensured by a knot system (komono) connected to a leather cord attached to the tsuka-gawa (kawa himo).
The guard is made of a round leather or plastic piece with a maximum diameter of 9 cm which is often held in place on the tsuka by means of a leather or plastic washer called tsuba dome.
In the past, the shinai was made exclusively of bamboo blades (take) split in four along its length. However, the practice of kendo can be very hard on the bamboo which crumbles and gets damaged during training.
The Japanese company Hasegawa has patented a shinai made of carbon fiber blades. The life span of the carbon shinai is better than the traditional bamboo shinai and the carbon shinai requires less maintenance.
The Japan Kendo Federation (ZNKR) has approved this weapon for use in competitions and tournaments.
Due to the production of low-cost shinai outside of Japan, the All Japan Budogu Cooperative (Zen Nihon Budogu Kyodo Kumiai) has developed a quality label for bamboo shinai in collaboration with the Zen Nihon Kendo Renmei.
This label guarantees that the shinai bearing it have been made from quality bamboo according to certain traditional methods. The label is a sticker on the shinai with the letters SSP (Shinai Safety Promotion).
Other labels exist, such as the SG label associated with the Japanese Consumer Protection Association, but the only label under the auspices of the Japanese Kendo Federation that guarantees the quality and conformity of shinai for competition is the SSP label.
The total length of the shinai is expressed in traditional Japanese units: the shaku (which is worth about 30.3 cm) and the sun (which is worth about 3.03 cm). A shinai 39 is a shinai of 3 shaku and 9 sun which is 3 x 30,3 + 9 x 3,03 = 118,17 cm.
The length, weight of the shinai (measured without the tsuba) and the diameter of the saki-gawa are regulated by limits depending on the age and sex of the practitioner.
In the two-sword technique (nito), a particular regulation is applied.
Because a shinai is subject to violent blows, it must be cared for before and during training.
The care of the shinai is an important part of kendo etiquette.
A bamboo shinai should not have any splinters or cracks that would endanger its integrity. For a carbon shinai, it should be checked that the outer layer is not damaged and that no carbon fibers are leaking out.
Furthermore, the tsuru should always be tight to prevent the sagi-gawa from coming loose, releasing the slats which could then pass through the partner's men's grid.
The naka-yui must also always be tight to hold the slats together. Not all shinai are of the same quality, but careful maintenance will significantly increase their life span.
For safety reasons, shinai are systematically and compulsorily checked before all competitions. Any shinai with the slightest defect or which does not comply with the standards is systematically discarded.
The shinai has become a popular weapon in the world of professional wrestling. It is very often called Singapore cane or kendo stick.
It is used by The Sandman, Steve Blackman, Tommy Dreamer, Justin Credible and Shane McMahon.