Believe it or not, as the Ninja Turtles began to gain popularity in the late 80’s and early 90’s, a company called Solson Publications teamed up with Mirage to put out official karate training manuals, featuring the turtles. What made these manuals unique, was that not only were they officially authorized, but they had legitimate karate instructions inside. Defeat the Shredder (or at least the neighborhood bully) with the skills you learned in the TMNT Karate Manual!
There was no attempt to sugarcoat these manuals or to make them into comics that “sort of” taught you karate moves. Instead, this manual (and the other 6 books in the series) played it straight and showed you legit karate manuevers and styles with Ninja Turtle art. It’s literally no different than if the artwork were regular humans, as all the other martial arts manuals out there are.
I have no idea if anyone actually ever used these to become a ninja master, but it’s pretty neat that these sort of things exist. The other martial arts manuals give you even more skills in defense as well as the basics of discipline. It’s really a neat part of the TMNT history.
Of course it’s not quite as interesting as a mutant rat teaching you the ways of ninjitsu in the sewers, but as a youngster growing up idolizing the TMNT, it was a great way to get into the martial arts. I wonder if this sort of stuff would slide these days in the Nickelodeon world? Probably not.