[4][5] Choi originally claimed that his father sent him to study calligraphy under Han Il-dong, who was also "a master of taekkyon, the ancient Korean art of foot fighting".

[5] In Kyoto, he met a fellow Korean with the surname Kim, who was a karate instructor and taught Choi this martial art.

[7] Just before he had left Korea, Choi apparently had a disagreement with a wrestler named Hu, and the possibility of a future confrontation inspired him to train; in his own words, "I would imagine that these were the techniques I would use to defend myself against the wrestler, Mr. Hu, if he did attempt to carry out his promise to tear me limb from limb when I eventually returned to Korea".

He wrote that he was imprisoned for attempting to escape and, in June 1945, was sentenced to seven years for conspiracy by a Japanese Military Court for his involvement in a rebellion.

In 1979 he traveled and defected to North Korea where he was welcomed by the government and supported in his project of spreading Taekwondo to the world.

[21] Choi died of cancer on 15 June 2002 in Pyongyang, North Korea,[5] where he received a state funeral in the Patriotic Martyrs' Cemetery.