 Upon commissioning , the sister ships were assigned to the 1st Battleship Division , although Nagato became the flagship of Rear Admiral Sōjirō Tochinai , a role she often fulfilled during her career . The ships hosted Edward , Prince of Wales , and his aide @-@ de @-@ camp Lieutenant Louis Mountbatten in 1922 during the prince 's visit to Japan . After the 1923 Great Kantō earthquake , both ships loaded supplies from Kyushu for the victims on 4 September . They sank the hulk of the obsolete battleship Satsuma on 7 September 1924 during gunnery practice in Tokyo Bay in accordance with the Washington Naval Treaty . Nagato became flagship of the Combined Fleet on 1 December 1925 , flying the flag of Admiral Keisuke Okada . The sisters were placed in reserve several times during the 1920s while they were being modernized . Mutsu served as flagship of Emperor Hirohito during the 1927 naval maneuvers and fleet review and again in 1933 . 
