In the evening of July 8, 1864 and around Sanjo-bashi bridge, Hachiro and his fellow, Gokichiro TOKOROYAMA were questioned by a group of guards of the Tokugawa shogunate who were carrying out guard duty due to strict security that ensued due to the Ikedaya Incident, and a fight using swords started, Hachiro killed two guards with his sword, and Hachiro himself was also injured.
元治元年6月5日夜、同僚の野老山吾吉郎と三条橋付近で、池田屋事件により厳戒警備中の幕府方に尋問を受けて斬り合いになり、2人を斬殺し自らも負傷。