by Donald Roley
The Nyoibo is a large (2 meters +) wooden club, about 10 centimeters at its widest point and narrowing down towards the handle, where it is about five centimeters wide. It was usually plated in metal, studded and was octagonal in the striking area, rather than purely round to increase the damage. A strap of some sort is usually found to help hoist the heavy weapon onto the shoulder.
The use of sticks as a back up or improvised weapon has a long history in all cultures and there is references and surviving examples from the Heian period through the Kamakura period (eighth to thirteenth centuries) of soldiers adding metal and studs to clubs and staffs to increase their lethality.
During the war of the northern and southern courts (In Japanese "Nambokucho" fourteenth century) the form we call the Nyo-ibo came into prominence during the protracted struggles over a few generations.
The term 'Nyoibo' seems to be unique to the Kukishin- ryu and it's variants, such as the Kukishinden- ryu and Hontai Kukishinden- ryu. This is not unusual as many schools have slight variations in non-standard weapons and have their own name for them. In general terms, the Nyo-ibo would be classed under the family of weapons called 'Kanasaibo', and that group contains weapons in length from a meter and a half to over three meters with many different methods of construction and width.
Eventually, under the mind set of 'if a little is good, more is better' it became common to make clubs entirely out of metal instead of wood reinforced with metal. The size had to be cut back to retain it at a weight that soldiers could carry around. This last form, popular during the sixteenth century when armor reached its peak and it became difficult to cut through it, was about a meter and a half (four and a half feet) long and about five centimeters at its widest point. Despite the fact that a blow with any of these massive weapons could crush all but the strongest armor, and the kinetic energy would still harm a person inside unbroken armor hit by this weapon, the emphasis on speedy maneuvers that characterized the last era of samurai battles made this weapon less popular.
This weapon was usually wielded by only the strongest of warriors. Even so, use of only the arms is impractical. To move with it, it is common to rest it on the shoulder and use the legs to propel it. When not able to do so, the arms are kept close to the body to allow the energy to be provided by the legs and not the arms. Striking with the Nyo-ibo is usually accomplished by letting the weight of the weapon fall on the opponent, or thrusting it into them usising the legs as a means of thrust rather than the arms. Placing the weapon so that the tip is on the ground and the handle is straight up provides for a semi- mobile shield with the wielder moving to the opposite side of the weapon from the attack and keeping the nyo-ibo between them. Use of the nyo-ibo requires the use of the entire body and that is its main attraction for study by taijutsu students.
Examples of this in action are few and not readily available. Aside from public demonstrations the best chance of seeing this weapon in action is in the tape "The Ninja Art of Grandmaster Masaaki Hatsumi Vol 1," which used to be available in English. It is still available in Japan through Bab Japan video productions under the title 'Ninpo Taijutsu No Okugi.' In it, Nagato sensei gives a good demonstration on its use and capabilities.
Sources for this include "Truth In Fantasy XV- Buki to Bogu, Nihon pen." by Toda Fujinori, Shinkigensha, Tokyo 1994. Special thanks to Isamu Shiraishi and Hiroshi Nagase for their patience in answering my questions.