Tohei left as a result of a disagreement with the son of the founder, Kisshomaru Ueshiba (植芝 吉祥丸 Ueshiba Kisshōmaru, 1921–1999), who at that time headed the Aikikai Foundation.
("Waka-sensei" means "young teacher," and applied to Moriteru Ueshiba when Kisshomaru Ueshiba was still alive; this usage also exists outside of aikido, and is a facet of senpai and kōhai.)
A collection of reflections on the philosophy of the founder of aikido together with some 80 photos of Morihei Ueshiba, Kisshomaru Ueshiba, Koichi Tohei, et al.