Nunchaku (ヌンチャク) is a martial arts weapon consisting of two sticks, usually made of wood or metal, connected by a chain or rope. In Chinese martial arts, the weapon is called Shuāngjiégùn (双节棍), while in Filipino martial arts it is known as Tabak-Toyok. The origin of the nunchaku is unclear, but the oldest written source mentioning it is the over 1000-year-old Chinese manuscript Wuijing Zongyao (武經總要), which describes various aspects of Chinese martial arts. It is likely that the nunchaku evolved from common everyday tools such as flails or horse bridles.

The nunchaku gained significant international attention in 1972 through the film Fist of Fury, where Bruce Lee uses the weapon. This led to a dramatic increase in its popularity. Dan Inosanto, one of Lee's top students and a master of Filipino martial arts, taught Lee how to use the nunchaku. Inosanto was also a black belt under Ed Parker, the founder of American Kenpo Karate. During his black belt test in Kenpo, Rick Avery demonstrated his self-constructed Nunchaku Set, which Parker appreciated so much that he included it in Ed Parker's American Kenpo Karate (EPAK) as a requirement for the second-degree black belt.

Parker's interest in nunchaku was substantial, and he explored its use according to "The Principles of Motion" which form the foundation of EPAK. The result was the book Ed Parker's Guide to the Nunchaku (1975), which covers the basics of using the weapon. An interesting anecdote is that Parker used this material as the basis for his promotion from ninth-degree black belt to tenth-degree. He continued to teach nunchaku until the end of his life. Here is a clip from a 1990 seminar where Ed Parker instructs in nunchaku techniques.

Goshin Kempo Karate (GKK) traces its origins partly to EPAK, and basic techniques (kihon) and forms (kata) with nunchaku from EPAK are a requirement for the fourth-degree black belt (4 dan, yondan). Below is a clip of Tommie Petersson (1st Degree Black Belt in EPAK, and 7th Dan Black Belt in GKK) performing the Nunchaku Set, as it is referred to in EPAK, or Nunchaku kihon kata as it is called in GKK.