"The Koga ryu of ninjutsu survived through the generations until the 1960s, when the unfortunate death of Fujita Seiko, the last possible Grandmaster of the Koga ryu (style) of ninjutsu, ended the ancient tradition. Before his death, Fujita claimed he did not, and would not pass on his Koga ryu to anyone. For more information on Fujita Seiko, visit the Fujita Seiko link on this site. The Iga ryu however, lives on in the Bujinkan."
From sites...
Bujinkan Kumogakure Dojo, North Carolina History
And many other associated sites Bujinkan sites;
Now another site held by the Bujinkan has these documents and says something quite different...
"In the 1978 revision, Watatani then summarized and reflected upon Fujita's information: "So here Fujita Seiko was the last soke of this ryuha and it was one of 6 ryu that belonged to the Minamiyama Rokke, maybe 6 strong families or an organization." He ends his reflection in a very telling way by writing, "also, nobody knows this ryuha today. I think he never taught it." This is a damning verdict from a man who is the author of Japan's official "Martial Arts Directory," a publication that is considered the authority in all matters of Japanese martial arts. This statement by Watatani, absent outright and validated evidence contradicting it, must be considered martial arts canon."
From
here
specifically under the "
Last Koga Ninja" section. Note that this actually well researched information which I find very creditable states that the writer of the interview says "I think he never taught it." One's guess (no matter how educated), do not suggest fact. And it certainly does not mean Fujita said so.
More so,
Fujita Seiko: The Last Koga Ninja or at
Fujita Seiko: The Last Koga Ninja page five of the image, note it states under the bold heading "The legacy of Saiko Fujita" that Seiko Fujita was an intelligence officer and had trained special forces and espionage forces in various aspects of Ninjutsu.
Such study was also gained by the Allied Forces after WW2 as a spoil of war, which is the basis for the British SAS claim to have studied ninjutsu long before Stephen Hayes & Ashida Kim and ninja-boom become know words...