Subtrope of Extranormal Institute.
Learning how to be a ninja is rather straightforward. Normally one learns from a personal master, or sometimes a dojo. But there are those that believe that learning the skills of a ninja can be made to look like a public school. After all, you call your ninja instructor "sensei", which means "teacher", so it's the same thing. Right?
Calling the instructor "teacher" is about the only thing ninja training has in common with schooling. There are no written tests, homework, or grades. You learn the skills and move on when you master them. Don't expect graduates of this Ninja School to act like real ninjas.
The comic Ninja High School is the Trope Namer, although it is not (usually) an example of this trope. Compare Wizarding School, especially in settings like Naruto where ninja have more in common with mages than actual ninja, and Spy School, where other types of secret agents learn their trade.
Compare the Rival Dojos.
- There's a three-year Ninja School in Konoha, and other ninja schools are assumed to exist in the other Hidden Villages (although little is known beyond that supposition).
- We know Hidden Mist has one because Zabuza graduated early before he was even enrolled by killing off an entire graduating class of students.
- Nintama Rantarou is a rare example of a Ninja School that actually teaches actual ninjutsu techniques and has students, graduates and teachers that act like real ninjas (when they carry out their missions). It's reasonably realistic.
- Ninja Academy is a spoof of this trope.
- Discworld: The Assassins' Guild in Ankh-Morpork would probably fit the trope as well, especially considering the inspired final test in Pyramids. On the other hand, the young gentlemen (and recently ladies) who study there receive such a well-rounded education, many upper-class families enroll their children only to withdraw just before the distasteful "final exam".
- To Be a Ninja is a series of novels by Benedict Jacka. A brother and a sister escape a drug baron father in a secret ninja school in Britain country. A third of the pupils are British, the others Japanese.
- They are never called ninjas, but the House of Black and White in A Song of Ice and Fire is basically a ninja school where acolytes are trained to become magically face-swapping Deep Cover assassins.
- In one of the Ninja Specials of Mythbusters, Grant, Tory, and Kari try ninja weapons and fail. The narrator suggests that they won't be passing Ninja School anytime soon.
- Power Rangers Ninja Storm has at least two, the Wind and Thunder Ninja Academies. Both are attacked in the season premiere, with only a handful of students avoiding capture - the rest spend the entire series held prisoner on the Big Bad's spaceship. Despite the elemental names, the Wind Ninja Academy teaches manipulation of multiple elements — Air, Earth, and Water. The Big Bad talks about the ninja schools as if there are way more than the two, or were before he wiped them out. The Super Sentai twin, Ninpuu Sentai Hurricaneger, is similar.
- That said, it's never clear whether the academies are full-time schools or just afterschool classes - it's impossible to tell since the regular lessons were suspended while the entire student body was missing. The Rangers did mention homework from time to time, but never said whether it was ninja homework or regular homework. We do, however, see an academy graduation, which is similar to normal school right down to getting "diplomas".
- The Scottish indie pop band Bis did a song called Ninja Hi Skool
It's cool! It's cool! It's cool cool cool! It's cool cool cool for YOU! NINJA HI SKOOL!
- In Dungeons and Dragons 5th Edition, it's assumed that monk characters were trained at a monastery that specializes in the eventual Path they will choose. Any monk who chooses the "Way of Shadow" is assumed to have gone to a Ninja School, though whether or not this is true is up to the player.
- The setting of Senran Kagura is a conflict between schools of 'good' and 'bad' shinobi. The franchise mix elements from light-hearted comedic highscool anime with some of the most serious ninja tropes : basically, the characters are cute highschool girls who cut down scores of other students.
- The established schools appear properly accredited as high schools, as their students have legal identities and potentially the need for a legitimate high school diploma and education. The Hanzo Academy is unusual in that rather than only serving the children of traditional ninja families, it's a public high school with a few secret facilities and classes and whose shinobi students mix with the general population. Hebijo is a much more straightforward ninja school.
- Therkla of The Order of the Stick mentions that she was valedictorian at Ninja School. A flashback panel reveals that she took the title using her graduation cap.
Therkla: I am salutatorian — no more!
- The Order's waiter at "T.G.I. Wednesday's" in Azure City mention she's working there to put herself through ninja school.
- The Huntsclan Academy in American Dragon: Jake Long. Rose even showed Jake that, despite the fact the students there are trained to slay magical creatures (there's even a class named "Dragon Slaying 101"), it was still a school by starting a rumor (Jake needed a distraction).
- Ron Stoppable in Kim Possible gets a special episode where he enters an exchange student program and gets sent to one of these. It partially averts this trope by being a live-in dojo secluded in the mountains, but it still has classes and school staff.
- The Nickelodeon cartoon Shuriken School is set at one.
- On Chop Chop Ninja, the characters train at Chop Chop Academy to become the next "Chop Chop Ninja".
- "Dojo" is a term that can refer to a formal training place for any of the Japanese martial arts. The concept of a dōjō as a training place specifically for martial arts is a Western concept; in Japan, any physical training facility, including professional wrestling schools, may be called dōjō because of its close martial arts roots.