The debate he had with Nagashige IKEDA, who was the uncle of his wife and ronin (masterless samurai) in Kyoto at that time, led to a violent quarrel and fight in midnight of August 7, 1658, which caused Nagashige to die instantly and Yoshiharu himself to die from injury on the next day.
明暦4年（1658年）7月9日深夜、妻の叔父で、当時は京都で浪人していた池田長重と対談中に口論となって刃傷沙汰に及び、長重は即死し、嘉治も翌日に傷が元で命を落とした。