Juntendo University
After graduating, Inokuma became a judo instructor for Juntendo University and the Tokyo Metropolitan Police Department. In 1965, he entered the Open weight class of the World Judo Championships intending to wrestle Dutch judo champion Anton Geesink, but Geesink went to the +80 kg division that year, and the two never faced off against one another. Both Geesink and Inokuma won gold medals in the competition, and Inokuma announced his retirement shortly afterwards, citing lack of motivation.