A quick note about Ninjutsu/Ninja/Ninpo etc...
It is common for people in the Bujinkan (online that is) to say they only have three Ninja Schools and six samurai schools. This was a recent parroting of about the last six or seven years for the most part.
I believe this stems from people getting "half truth" information from online resources and then spreading it.
Ninjutsu Ryu focus on *Ninjutsu* stealth, spying etc. If it has Taijutsu and weapons, then they are designed for people who would be in spying situations. Look at ton so no kata for example.
Some schools like gyokushin ryu, kumogakure ryu etc.. Assume a foundation in some sort of taijutsu and just have specific hints and suggestions for certain situations. With most of what is written down, being about infiltration, spying, poison, weather considerations strategy etc...
THIS is Ninjutsu!
Now, we also have schools of Taijutsu, Ninja of course had their own Taijutsu, in the Takamatsuden tradition, the ninja had a base in the kosshi jutsu and koppo jutsu of both gyokko Ryu and koto Ryu also connections with the daken taijutsu and ju taijutsu of shinden fudo ryu!
These schools were not "Ninjutsu", but they WERE the taijutsu on NINJA!
Think of it like this...
You are in the army, you learn basic hand to hand and weapons use. In the USA army today, they have a manual, that manual is like a densho. What they are learning from that manul is like "their" ryu of taijutsu (just like gyokko ryu for example)
Now some of them go on to study how to be spys. What they learn there is specific for being a spy. It has it's own collection of information, this would be like a "Ninjutsu" ryu, like Togakure ryu.
But, when a "spy" has to fight hand to hand, he uses the system the army teaches all enlisted aong with his special training. See?
So while it is true that there are four schools of "Ninjutsu" passed down from takamatsu which are:
Togakure Ryu
Kumogakure Ryu
Gyokushin ryu
And certain books from kukishin/Amatsu tatara
There are ALSO the following schools used by Ninja as their form of taijutsu
Gyokko Ryu Koshi Jutsu
Koto Ryu Koppo jutsu
Shinden Fudo ryu Danken taijutsu
Shinden Fudo Ryu Jutai jutsu
I can even say kukishin Ryu, because kukishin has actual ninjutsu teachings at the higher levels, so thoise people who would do those teachings were "Ninja" and their system was Kukishin Ryu Ninjutsu
(It should be noted that takamatsu Sensei was going to promote kukishin Ryu Ninjutsu instead of Togakure ryu. Fact is MOST of Togakure ryu IS from kukishin Ryu scrolls word for word!)
So the "Ninja connection" is in almost every art we do Genbukan ninpo/Bujinkan. We must also note that in the case of genbukan, what we study is PURE Ninpo meaning it is a composite art, Genbukan Ninpo Bugei, historically most all the arts in it were used by ninja, though regardless, today, they are all Genbukan NINPO BUGEI which "could" be considered a new ninpo Ryu based on the combination of the older ones.
Regards,