Later, he engaged in forging an alliance between Satsuma and Tosa, starting with successfully forming a secret pact between Taisuke INUI (also known as Taisuke ITAGAKI) of Tosa and Tatewaki KOMATSU and Kichinosuke SAIGO of Satsuma on June 23.
その後、薩土同盟についても同様に奔走し、まず、5月21日（旧暦）、土佐の乾退助（板垣退助）と薩摩の小松帯刀・西郷吉之助との間で倒幕のための薩土密約締結に成功する。