It is said that when Ryoma SAKAMOTO submitted Senchu Hassaku (the basic outline of the new regime drawn up by Ryoma SAKAMOTO) to Takamori SAIGO and stated that '[he] shall be the Kaientai of the world,' Mutsu, who was also present, was greatly impressed and took every chance to mention the reminiscence in later years.
坂本龍馬が船中八策を西郷隆盛に提示した際、「わしは世界の海援隊をやります」と発言した場に同席し非常な感銘を受け、後世ことあるごとに回想を語ったとされている。