The Kuji-Kiri were the Ninja's Nine Levels of Power. They were 1. Rin - Strength of mind and body. 2. Kyo - Direction of energy. 3. Toh - Harmony with the universe. 4. Sha - Healing of self and others. 5. Kai - Premonition of danger. 6. Jin - Knowing the thoughts of others. 7. Retsu - Mastery of time and space. 8. Zai - Control of the elements of nature. and 9. Zen - Enlightenment.
Widely considered to be the movie that popularized Ninjutsu during the 1980s, the movie was actually the second major English-language Ninja film of the 1980s as it was preceded by Chuck Norris' The Octagon (1980).
After Mike Stone was let go because of his lack of acting ability, Director Menahem Golan found out that Franco Nero was in Manila and quickly approached him for the role and Nero agreed to do the film. Stone stayed on the film as Nero's stunt double and it is Stone who handles the majority of the action sequences as the ninja.
Menahem Golan said of this movie after being asked about this film kick-starting a ninja craze: "It started when Chinese karate films became popular. I looked for something new in Asian martial arts and found information about the Ninja culture in an encyclopedia. The Ninja were middle-class people in Japan--lawyers, government clerks, etc. It was a secret organization that helped the feudal government. It actually preceded the Chinese karate battles. They used very special methods, developing their sixth sense. That fascinated me and I said I could write story ideas out of it, so we made "Enter the Ninja" and American Ninja (1985) later on. Many imitations followed".
Ninjas are seen in this movie with a full wardrobe of attachments and weapons. These often included a blow-gun, bola (manriki), bow & arrow, nunchaku (nunchuks), sai, shinobi-gatana, shiroken, spear-staff and tonfa.
The first of three "Ninja" movies in Cannon's Ninja series. The second and third films were Revenge of the Ninja (1983) and Ninja III: The Domination (1984). Both sequels were unrelated in terms of story. Cannon also went on to make American Ninja (1985) which spawned its own franchise which went to five movies.
First major role in an English-language film for Shô Kosugi, an actual ninpo practitioner who was also the movie's technical advisor and fight co-ordinator. Kosugi starred in numerous other 1980s ninja movies and appeared in each of this film's sequels but playing different characters.
When this film was being developed and made, the novel "The Ninja" by Eric Van Lustbader had been published in April 1980 and had become quite popular. This movie is not an adaptation of that book which to date [December 2012] has never been filmed.
This film is widely attributed to being the movie that popularized Ninjutsu during the 1980s as several ninja movies were made after it. Prior to the film, judo films had been popular in the 1950s; karate movies in the 1960s and kung-fu pictures in the 1970s.
The film's original press kit declared: ". . . the first Western film to deal solely with the mysterious and elusive art of Ninjutsu. It will set the trend in Martial Arts films for the '80s, making them the decade of the Ninja . . .". It added, "In the late fall of 1980, the concept for "Enter the Ninja" was brought to producer/director Menahem Golan. Having never produced a martial arts film, Mr. Golan was a bit difficult to convince at first. He assumed that everything had been done before in martial-arts films, but after he was told about the unique art of Ninjutsu, he immediately began preparations on "Enter the Ninja".
Not only did Shô Kosugi play The Black Ninja in the film, but at the beginning he also plays one of the red ninjas. It is quite obvious in a two-shot of two red ninjas standing next to the pond; Sho is the red ninja on the right, which is evident by his distinct eyes and the accompanying black eyeliner.