Okay, I'm going to try to fill in all the gaps at once here, and be as comprehensive as is possible, as it may help to have a Ninjutsu person actually answer the question. To begin with, the term "Ninjutsu" is not as common as it once was, but we'll use it for the sake of convenience here. I'll explain. The major Ninjutsu-related organisations (and I'm talking about the legit ones only here) are the Bujinkan, Genbukan, and Jinenkan. There are also very legitimate off-shoots of these organisations, as well as not-so-legitimate ones, and quite a few people who have read a book or two, or heard some names it seems, and think that they can say they are teaching/studying the arts. So it's safest to stick with the Big Three until you know what you are really looking at. The Bujinkan could be looked at as the "father" of the other two (with Takamatsu Sensei being the Grandsire of the three). It's syllabus is made up of 9 distinct Classical Arts, some are Ninjutsu, the others are Bujutsu, and the Ninjutsu side has been sort of downplayed, as the focus of the Bujinkan is not Ninjutsu, it is on instilling the skills and philosophies gleaned from the variety of schools that make up it's curriculuum, and refer to it's teachings as Budo Taijutsu (Martial Ways of Body Techniques/Art), although many weapons are also taught. The Genbukan has a couple of associated groups, most notably the Kokusei Jujutsu Renmei (KJJR). They refer to their Genbukan syllabus as Ninpo, and it is made up again of a variety of old systems, primarily coming originally from the Bujinkan, although they have been supplemented/added to others that Tanemura Sensei learnt after leaving the Bujinkan. They teach Bujutsu/Jujutsu in the KJJR, so the Ninpo/Ninjutsu portion that you can learn is kept aside there. This is possibly the best if you are after Ninjutsu only. The Jinenkan is headed by Manaka Sensei, one of Hatsumi Sensei's (head of the Bujinkan) first students. He teaches 7 systems, six of which come from the Bujinkan (Togakure Ryu Ninpo Taijutsu being the most "ninja" of all the various schools, Koto Ryu and Gyokko Ryu both having links to Ninjutsu and Ninja groups in the past, Kukishin Ryu, Shinden Fudo Ryu, and Hontai Takagi Yoshin Ryu being more "samurai", or classical Bujutsu), and the seventh being the Jinen Ryu, Manaka Sensei's own creation based primarily on sword and Jutte. Within the Genbukan and Jinenkan curriculuums you will have the opportunity to learn individual systems, within the Bujinkan this is far less common, as their focus is on the skills, and the others on the correct transmission of the old schools. Neither is better, by the way, just better suited to individual students. So as you can see, few legit groups will actually even say they are teaching "Ninjutsu", instead using other terms to show the range of sources that their teachings come from. So what is entailed in that syllabus? Oh, lots! I'm going to be rather general here, as it will cover a variety of the different Ryu that make up each organisation, but it should give you a bit of an idea. First off is the unarmed combat. This can be divided up into various groupings, most commonly Jutaijutsu (grappling, most commonly standing up, throws, limb controls and locks, chokes, escapes, etc) and Dakentaijutsu (striking, kicking, blocking etc), possibly with Taihenjutsu (rolls, breakfalls, escapes, junan taiso body conditioning etc). But then we also get groupings such as Koppojutsu (Koto Ryu, Gyokushin Ryu, Kumogakure Ryu, some accounts I have seen of Togakure Ryu's classification, and I would agree with that one), and Kosshijutsu (Gyokko Ryu, sometimes Togakure Ryu as well), Taijutsu (Shinden Fudo Ryu, Togakure Ryu, refering to it's system as Ninpo Taijutsu, Asayama Ichiden Ryu, and others), Yoroi Kumiuchi, and a few others. And just because two arts use the same or similar names doesn't mean they have similar characteristics.... There is also a large range of weapons taught, primarily from the Kukishin and Kukishinden Ryu, although some come from Togakure Ryu, a few from Kumogakure Ryu, and a few others from other systems, such as Manriki Gusari being brought over from Masaki Ryu and integrated into Gyokko Ryu. The weapons formally taught in the scroll material from these arts include various staff weapons (Rokushaku Bo, Yonshaku Jo, Sanshaku Bo/Hanbo, Te Giri Bo), swords (Shinobi Gatana, Katana, Tachi, Kodachi), pole arms (Yari, Kama Yari, Naginata, Bisento), Shuriken, Shako (hand claws), Jutte, and others. Some weapons not covered in the scrolls formal techniques themselves, but still taught include Kyoketsu Shoge, Kusari Gama, Chigiriki, Nagamaki, Nito Ken (although the Jinen Ryu has formal techniques for this), Kunai, and many more. Add to all of this most schools teaching modern weapons, such as knife, pistols, walking canes, and many more, really only limited by the instructors skill and experience. So that pretty much covers the physical technical syllabus. As to your question about learning the stealth and concelament side of things, well, that will depend on the instructor in question. The information is there, as part of the Togakure Ryu scroll, and it is something that I have taught myself late last year. However, it was taught more for entertainment value, and isn't really taught often. We have taken the concept into modern times, though, and taught such things as anti-surveilance (to avoid being "marked" by criminals looking for a victim) and more. So it's there, but don't expect it to be focussed on. There are many "fundamentals" to the arts, particularly as each organisation takes it's curriculuum from so many sources. The most well-known are things such as the Kihon Happo and Sanshin no Gata, there are many others, and these are all only able to be learnt from an instructor. So I won't really give a description here, as words can't really do it. They are as much about getting the pinciples and feeling of the art as they are just getting the physical movements. How long does it take? Oh, the age old question. Honestly, it takes as long as it takes. Don't ever look to rush these things, as you will miss all the subtleties that would get you to that level. Depneding on the organisation, each with very different ranking systems and criteria, different level will be reached in different amounts of time, and with different levels of skill in different areas. The important thing is to start, and then keep going. If you do that, then the rest looks after itself, so don't worry. Hope this has made some sense to you. Any more questions, just ask.