When I lived in Japan, I was lucky enought to be invited to join Matsumoto Sensei’s practice club. At that time I was the most junior member of the group, so did not have the nerve to ask too many questions to or about him.
He achieved the grade of 9th dan, which is rare for a non professional sensei (not police or education sector) and he was unusual in that he explained the theory of waza in detail in a period when most instruction was of the JFDI kind. His motto was “Ken Ri”
I was aware that he studied with the great pre war sensei from pictures of Saimura, Mochida and Nakakura in his home. His chudan was acknowled to be exceptional, see the pic above!