Zamenhof being the creator of Esperanto in 1887.
So I was wondering if you or someone else on the forums knew if Esperanto was used while O sensei was active and if O sensei ever learned or spoke Esperanto?
Thank you for your kind words.
Esperanto was used while O Sensei was active in Omoto, but there is no evidence that O Sensei ever studied the language and Deguchi Onisaburo apparently did not speak it very well.
Esperanto initially had a distinctly radical tinge. The Japan Esperanto Association was founded in 1906 through the efforts of an anarchist named Osugi Sakae and the radical Kita Ikki called for Esperanto to become a second language in Japan (with the abolition of English), in order to diminish western influence.
Later the movement became more mainstream and by 1926 there were 181 registered groups in Japan with over 6,000 students. Omoto began to promote Esperanto in 1922, as part of the new-style socially approved Omoto, after the First Suppression in 1921. (This was just after O Sensei moved to Ayabe.) The promotion activities continued right up to the Second Suppression in 1935.
However, Morihei Ueshiba's move to Tokyo lessened his contact with Deguchi and I would think that Ueshiba had enough to do with running the Kobukan Dojo to find time to learn Esperanto.
There is no trace of Esperanto (as far as I can recall) in Kisshomaru Ueshiba's biography.