Actually, that title belongs to Joseph Greenstein, the Mighty Atom
, who jumped ship in Yokohama and trained in some kind of jujutsu there, one of the first non-Japanese ever to do so, in, IIRC, 1905. What isn't mentioned in the Wikipedia article is that the training regimen he followed as a kid, learned from the circus strongman, included a lot of specific breathing exercises. (And my favorite "feat of strength" listed in the article is - "Beating up 18 Nazis with a baseball bat." - times were different then - the judge praised him for it)
Beating nazis and the Klan with baseball bats! Fantastic!
I used to work for a hell of a karate man named Ron Epstein who joked about using jew-jutsu. He was a direct student of Mas Oyama. He's still out there kicking around, from what I hear. Nearly 80 now, I think.