As a side note, over dinner I tried to point out this book to you regarding a certain individual, which if I recall correctly, was the same Takaoka Sadao you referred to. The book in question is "The Mysterious Power of Ki" by Kouzo Kaku, starting from page 123.
I think we have discussed the late Sadao Takaoka before. He used to head the Wakayama Kenshibu and always took part in the annual All-Japan demonstration in May. From talking to aikido friends in Tanabe, I understand that Takaoka was yet another of of those disciples with whom Morihei Ueshiba had direct personal contact (like Abe Seiseki and Michio Hikitsuchi), apart from any official relationship with the Aikikai, headed by Kisshomaru Ueshiba. If you can access the Japanese version of Google, you can find a fair amount of information.
Kaku Kouzo has written many books in Japanese. His articles in Aikido Tankyu
were quite informative. They were mini-biographies of Abe Tadashi, Murashige Aritoshi and Shirata Rinjiro, but not, surprisingly, of Sadao Takaoka. I have not read The Mysterious Power of Ki
, but will receive it in a day or two from Amazon Japan. I suspect that is a one-off English version produced with other authors & translators. I will let you know what I think of it when I have read it.
Miyake Hitoshi has produced a similar book, entitled The Mandala of the Mountain: Shugendo and Folk Religion
. Miyake is an acknowledged scholar of shugendo and has produced some very good work. The English book is a collection of essays and chapters published elsewhere, cobbled together as a book. I think the translators would have done better to focus on a single substantial work, such as his Shinto and Shugendo: The Rise of Popular Religious Thinking