Chris Parker
Grandmaster
Absolutely. For me, Koto is a Ninjutsu art due to it's history with heads such as Momochi Sandayu, along with Gyokko Ryu. However, it has been used by Ninjutsu groupings as well as Samurai, so we could go either way with it.
As for the individual focus, Koto being Koppojutsu and Gyokko being Kosshijutsu, I see those as being the aspects of the original Ninjutsu systems that have been preserved. You may recall that arts like Takagi Yoshin Ryu began as a weapons-based system, coming out of (primarily) 2 arts focussed on Sojutsu, with the Jujutsu portion only beginning from the second head, who had some run-ins with the head of the Takenouchi Ryu, and found his Jujutsu sadly lacking. Later, when it came in contact with Kukishin Ryu, it dropped it's weapon systems in favour of Kukishin's, with Kukishin leaving behind it's original Jujutsu syllabus in favour of the Takagi methods (to elaborate, the modern teachings of Kukishinden Ryu Dakentaijutsu are either from an earlier branch school, or, as some think, constructed by Takamatsu Sensei to combat the more popular karate and judo that was around. According to the same theory, at this time, and possibly in conjunction with Takamatsu Sensei, Ueno Takashi developed his Tenshin Koryu system for the same reasons).
With Koto and Gyokko, both systems originally had much larger syllabus', including a range of weaponry. Gyokko was said to feature Bo, Tanto, Spear, and Sword (Tachi), whereas Koto was very similar, but had some unique aspects to it's swordsmanship, such as Mangetsu no Kamae (to collect rain in the bo-hi), and a left-handed grip (to make the opponent think you were an amateur. So they were originally ninjutsu arts, but most of that has probally been lost, only Hatsumi Sensei could tell you for sure.
As for the individual focus, Koto being Koppojutsu and Gyokko being Kosshijutsu, I see those as being the aspects of the original Ninjutsu systems that have been preserved. You may recall that arts like Takagi Yoshin Ryu began as a weapons-based system, coming out of (primarily) 2 arts focussed on Sojutsu, with the Jujutsu portion only beginning from the second head, who had some run-ins with the head of the Takenouchi Ryu, and found his Jujutsu sadly lacking. Later, when it came in contact with Kukishin Ryu, it dropped it's weapon systems in favour of Kukishin's, with Kukishin leaving behind it's original Jujutsu syllabus in favour of the Takagi methods (to elaborate, the modern teachings of Kukishinden Ryu Dakentaijutsu are either from an earlier branch school, or, as some think, constructed by Takamatsu Sensei to combat the more popular karate and judo that was around. According to the same theory, at this time, and possibly in conjunction with Takamatsu Sensei, Ueno Takashi developed his Tenshin Koryu system for the same reasons).
With Koto and Gyokko, both systems originally had much larger syllabus', including a range of weaponry. Gyokko was said to feature Bo, Tanto, Spear, and Sword (Tachi), whereas Koto was very similar, but had some unique aspects to it's swordsmanship, such as Mangetsu no Kamae (to collect rain in the bo-hi), and a left-handed grip (to make the opponent think you were an amateur. So they were originally ninjutsu arts, but most of that has probally been lost, only Hatsumi Sensei could tell you for sure.