Re: "Hidden in Plain Sight" - Takeda Sokaku
Among his other students in that time period we could look at Sato.
He was more than a Kyoju Dairi; he apparently was a friend and trusted confidant, furthering the humanity of Takeda. He was the one the kids turned to to ask Takeda to come home and not travel so much.
He was also the one to whom Takeda turned to deliver a letter he dictated to him to personally deliver to Ueshiba. Curiously in the same time period being discussed (30's) Wherein the general tone was "Why are you lying about me and our relationship?
The Ueshiba family supposedly has further correspondence between the two men that they would not disclose to Stan.