I came across this paper about a fourth aim of Judo, beyond of the traditional three: taiikuhō (physical education method), shushinhō (morality method) and shōbuhō (attack and defense method). Very little information is available about this concept in English. The paper is in Japanese, only the abstract in English.
"The Introduction of the Concept of 'Ishinho' to Judo and the Thoughts of Kano Jigoro" by Shusaku KIRYU
https://www.jstage.jst.go.jp/article/budo/43/1/43_1_27/_pdf
"The Introduction of the Concept of 'Ishinho' to Judo and the Thoughts of Kano Jigoro" by Shusaku KIRYU
https://www.jstage.jst.go.jp/article/budo/43/1/43_1_27/_pdf