Each of the Teenage Mutant Ninja Turtles has mastered individual aspects of the 18 disciplines of ninjutsu, giving all four certain characteristics and abilities that the others do not yet possess. However, there are twelve other disciplines in ninjutsu, and anyone studying the art must excel at them. These disciplines can be split into combat and intellectual skills. The combat skills aretaijutsu, kayakujutsu, hensojutsu, shinobi-iri, choho, and itonjutsu.
Taijutsu is the art of hand-to-hand combat, and covers all forms of empty hand fighting technique. With its focus on grappling and striking, taijutsu has been adapted into several different martial arts, including jujutsu, judo, and aikido. Kayakujutsu is the art of pyrotechnics. This discipline involves using firearms and explosives in combat, and was developed at a time when little was known about chemistry, creating certain mysticism around the art. So when it was incorporated into ninjutsu, novices were taught about converting the more general element of earth into that of fire.
Shinobi-iri is the art of stealth and entering, and mastery allows the ninja to move without detection from friend and foe alike. Choho is the art of espionage, and allows a ninja to observe his foes to gather information. Itonjutsu is the art of escaping and concealment, and when combined with shinobi-iri becomes a potent force that should guarantee a ninja’s complete and total assimilation into any situation.
The Teenage Mutant Ninja Turtles have all shown their adeptness at these combat skills during every incarnation. Taijutsu is an important part to Raphael and Michelangelo’s fighting ability, since their sai and nunchaku require close quarters to use properly.While the turtles have never been heroes to use guns, the mechanics behind combustion are important to many of Donatello’s inventions. All of the turtles have used explosions when needed, and understand enough to know how to cause them. The boys have also shown strength in choho, especially Leonardo. This discipline requires focus and patience, something that all the boys have to a certain degree, but Leo is stands above the others in this area, thanks to his rigorous dedication to ninja training.
Hensojutsu is, however, one discipline that the turtles can never truly master. Disguise is an important element for the shinobi, and there were times when the boys were easily able to blend in (such as the third feature film, when they were entirely covered by bulky samurai armor). But as giant mutant turtles, they will never truly disappear into the everyday appearances of humans. The trench coat look works from time to time, but it’s still not a perfect disguise.
Shinobi-iri and itonjutsu are also areas where the turtles need to refine their skills. Over the years, Master Splinter has stressed the importance of remaining unseen. That requires extremely precise mastery over the arts of stealth and concealment. Due to their own attitudes and fearlessness of the human world, the boys have not always exercised these skills, and are not afraid to abandon them in lieu of just getting the job done or having a good time.
The combat skills of ninjutsu allow ninja to become master assassins. Each of the Teenage Mutant Ninja Turtles has grown strong in these areas to some degree, and they have exhibited the fruits of their labor on more than one occasion. While none of them have completed the training just yet, they are all on their way to becoming masters of ninjutsu. However, combat is only half the equation, and the intellectual skills must be assimilated as well.