Shioda graduated from Takushoku University, where he went to class with Judo master Masahiko Kimura and Kyokushin Karate founder Mas Oyama, in 1941, and was posted to administrative positions in China, Taiwan, and Borneo during World War II. In one incident in China, he was drinking in a bar with an army friend in Shanghai when the friend got into an argument with a local gang member. Three of his fellow gang members came to his assistance. Shioda and his friend were cornered by the gang. In the ensuing fight, Shioda broke the leg of one of the gang members, the arm of another, and stopped another by punching him in the stomach, all using his aikido skills. Shioda later described this incident as his 'aikido enlightenment' and wrote that one could only truly appreciate what aikido was about once one had used it in a life-or-death situation.