On 4 September 1923 , '' Mutsu '' loaded supplies at Uchinoura Bay , Kyushu , for the victims of the Great Kantō earthquake . With her sister '' Nagato '' , she sank the hulk of the obsolete battleship on 7 September 1924 during gunnery practice in Tokyo Bay , in accordance with the Washington Naval Treaty . Captain Mitsumasa Yonai , later Prime Minister of Japan , assumed command on 10 November . The ship was transferred to the reserve on 1 December 1925 . '' Mutsu '' served as flagship of Emperor Hirohito during the 1927 naval manoeuvres and fleet review . Captain Zengo Yoshida relieved Captain Teikichi Hori on 10 December 1928 . On 29 March 1929 , the ship was assigned to Battleship Division 3 , together with three light cruisers
Great Kantō earthquake
1923 Great Kantō earthquake
Japanese battleship Mutsu