However, when the bakufu (Japanese feudal government headed by a shogun) put up notice boards on Sanjo-ohashi Bridge to criticize the Choshu Domain (accusation of guilt), extremist supporters of a noble cause who opposed the accusation, including Masakatsu, decided to remove the notice boards with a total of seven persons including his superior warrior Sukegoro MIYAGAWA and his colleague Kichigoro FUJISAKI.
しかし、幕府によって三条大橋に長州藩を非難（罪状告発）する制札が立てられると、これに反発した正勝ら、過激派の志士は上士・宮川助五郎、同僚・藤崎吉五郎ら7名とともに制札撤去に乗り出す。