Fujita was said to be a Kouga Ryu Soke and while he did have a Kenpo connection he is not the one. Fuijita and his top students passed away in a car accident. Some of what Fujita taught did make its way into a certain style of Karate but thats a whole other issue.
It is not Fujita that this connection is. It is the Yoshida Ryu its self has connections with a different ninja ryu... Copy and paste that link.
http://cclib.nsu.ru/projects/satbi/satbi-e/martart/japan/heki.html
The real question is how does Ninjutsu-relate to Kenpo
the connection in my opinion is in 3 areas possible more then that.
1. is that as spy craft its origins are chinese (Sun Tzu chapter 13).
2. There are techniques which focus on suddenly being attacked you respond by quickly killing the "samurai that busted ya" now if we were all peace loving monks I doubt the focus of the peace loving monks martial art would involve a focus on killing
3. There is Mitose's focus on "evasion arts"
4. Mitose has a connection to Morhei the founder of Aikido and Morhei had knowledge of some ninjutsu escape or evasion techniques that he demonstrated at times. Where did Morhei learn Ninjutsu from? Well if you say it was in Aikijujutsu that he learned...
5. Yoshida Ryu has also teachings of aikijujutsu then you can say that ninjutsu has some elements in parts of Aikijujutsu. Or you could say that he learned them from Mitose. In which case Mitose learn the "shinobi" art of Yoshida Ryu.
6. Mitose seemed to have been described on a few occasions as a spy for the US against the Japanese
that is ironic with a shinobi being a spy and all.
7. The Yakuza have knowledge of both some ninjutsu like elements though Ninjutsu folks dispute that and Kenpo, Mitose seems to have been a criminal if that is the case its possible he had ties to the Yakuza and they taught him Kenpo. And if you think thats a far fetched conspiricy theory (I do too lol) I have herd of the Yakuza not being to happy about the system they teach being taught by some American teachers of Kenpo...
8. One last thing while it has been stated by some that the Ninjutsu unarmed combat method is known as Taijutsu, I have herd of a sort of sub system that focuses on striking the eyes throat and groin as well as another part that deals in nerve and muscle attacks
while these sub-systems have there origins in Chinese Chuan Fa the same with some parts of daito ryu.
9. Lastly I have herd that a Yoshida named Yoshida Kotaro focused on a small circle in-fighting speciality rather then the grappling and projections that one normally associated with Yoshida Ryu.
I think because of the Yoshida Clans vast connections to so many martial arts it is possible that in their long history they had members who knew Kenpo. Why does the Kenpo of Mitose resemble Okinawan Kenpo? I feel this is because both Okinawan Kenpo and Japans Kenpo are the same in that they both come from the same source and its possible that the Kenpo that came into the Yoshida line first made a stop in Ryu Kyu Islands.
Further more the Daijiten does include Kosho Ryu as an Okinawan Style but does not list a lineage for it. In that case it could be because it was part of the Yoshida Ryu and Yoshida lineage was already listed they didnt list it again, since they probably knew that Kosho Kenpo was more or less a sub system in Yoshida Ryu's Shinobi arts.
Most of this is just my thoughts from what I have discovered in the short time since my first post. I know in regards to the Ninjutsu stuff I been rather vage and I apologize to the Ninja fans who would rather a more correct useage and explanation of Ninjutsu then the one I gave.
Before anyone brings up Hatsumi, I will note that Togakure Ryu's lineage is credited to a Chinese Sage
called by the Japanese Kane Doshi who taught Daisuke Togakure so even they have a chinese connection with there ninjutsu. Again no offense intended I was just tossing out my thoughts.
Respectfully
Sami