The ship's reconstruction began on 18 December 1930 at the Yokosuka Naval Arsenal where her machinery was replaced, her armor was reinforced, and torpedo bulges were fitted. Yamashiros armament was also upgraded and her torpedo tubes were removed. Captain Chuichi Nagumo assumed command of the ship on 15 November 1934, her modernization was completed on 30 March 1935, and she became flagship of the Combined Fleet. Captain Masakichi Okuma relieved Nagumo on 15 November and he, in turn, was replaced by Captain Masami Kobayashi on 1 December 1936. Yamashiro began a lengthy refit on 27 June 1937 and Captain Kasuke Abe assumed command on 20 October. Her refit was completed on 31 March 1938 and Captain Kakuji Kakuta relieved Abe on 15 November. In early 1941, the ship experimentally launched radio-controlled Kawanishi E7K2 floatplanes. Captain Chozaemon Obata assumed command on 24 May 1941 and Yamashiro was assigned to the 1st Fleet's 2nd Division,Skulski and Preston use Squadron while Hackett uses BatDiv, presumably Battleship Division. consisting of the two Fusō-class and the two s.
