At the very end of the Edo period when the Satsuma clan and Choshu clan formed Satsuma-Choshu Alliance to promote the movement to overthrow the Shogunate, the Tosa clan, which supported the parliamentary regime theory and the Shogun's returning the sovereignty to the Emperor, submitted a petition for Taisei Hokan (proposed and planned by Ryoma SAKAMOTO in cooperation with Shojiro GOTO) to the Shogun Yoshinobu TOKUGAWA through the lord of the domain Toyoshige YAMAUCHI on October 29, 1867.
薩摩藩と長州藩が薩長同盟を結び倒幕運動を推し進めていた幕末も大詰めの時期、公議政体論を主張し将軍の政権返上を政治路線として考えていた土佐藩は、慶応3年（1867年）10月3日(旧暦)に（坂本龍馬が発案計画し、後藤象二郎協力）大政奉還の建白書を藩主山内豊信を通じ将軍・徳川慶喜に提出した。