Conan and Sonoko arrive at a dojo in Osaka where Kyogoku is training. Takami, the master of the dojo, once provided Kyogoku with a great deal of help with his karate training. While Conan and Sonoko watch the children practice, Kajiyoshi shows up to ... (more)get Takami's signature on their agreement. Operating the dojo has become difficult to the point that Takami has taken out a loan, and he is considering selling the dojo. Later, an important black belt is stolen from the dojo's display case. When Kyogoku is suspected of stealing the belt, he challenges Takami to a fight. If he wins, the dojo will remain open, and if Takami wins, he'll return the belt...