elder999 said:...Richard Kim once said that Choi studied with Yoshida Kotaro-and that Choi’s Japanese name was also Kotaro-though they were not related at all. This may contribute to the whole “adapted son” theme, though.
In any case, Choi was in Japan, and learned something there-before he called it hapkido, he called what he was teaching in Korea yawara, which is a lot like saying “jujutsu” in a very (even more?) generic way.
In the end, we’ll never know for sure: there are lots of reasons that Choi’s name might not appear on a register, even though he studied-nationalism, odd relationships-someone once suggested that he just “peeked in the door” and gleaned enough info that way, which would be waaay impressive, considering the product. All the players who could answer are dead, though-
Thank you for this very lucid and sensible perspective on this whole question.
Anybody who has experienced both Choi's art (as interpreted by any of his significant direct students) and Daito Ryu will immediately see and feel similarities. Choi's art definitely used aiki.
It seems clear that Choi learned some form of aiki-based Jujutsu during his time in Japan. As several people have pointed out, we may never know what that art was.
The probability that Choi learned Shotokan in Japan is virtually nil. There is little to no similarity between his original art and Shotokan, TKD or any other Karate-based art. Even in the HKD styles that use a lot of kicking (which Choi did not use), many point out that their kicking techniques differ from the corresponding TKD techniques.