Koppōjutsu is a subset of kosshijutsu. Although this part of the method provides an easily misleading definition, which says that koppōjutsu is “linear attacks with bone and against the bone structure,” etc. Broken bones are a result of koppōjutsu, yet no description of the purpose of the method.
If kosshijutsu is characterized by “volatility”, Koppōjutsu would than be defined as “solid” or “hard”. The movements are precise, compressed, and characterized by both agility and stability. The opponent is given no chance in time and space for counter attacks. Despite the contradictions of metaphors between kosshijutsu and Koppōjutsu, they share the same basic principles. The koppōjutsu we practice derive from Kotō-Ryū (虎倒流), Gikan-ryū (義監流), Gyokushin-ryū (玉心流), and Kumogakure-ryū (雲隠流), all of which have a historical connection to Gyokko-ryū (玉虎流), which also contains koppōjutsu. In the 1800s there were relatively many ryū-ha that had koppōjutsu in their curricula, but because of the complexity of this system, they died out.
Koppōjutsu includes several logical effectors (ways of confounding the nervous system) in order to shock the nervous system of the opponent. It includes among others the use of “Kakushi Buki” (concealed weapons; 隠武器). Although methods such as Sappō (killing methods; 殺法), Kappō (healing methods; 活法) and Suiren (swimming exercises; 水泳) are all part of our koppōjutsu. Just water training, according to Hatsumi Sensei is very important to practice and improves one’s proficiency in koppōjutsu. Another historical name of koppōjutsu has been “gohō” (methods of resistance; 禦法).