Musashi was the second Yamato-class battleship. Mitsubishi laid her down at Nagasaki on 29 March 1938, as hull number 800. She was launched in secret on 1 November 1940. A liner was moored alongside so the new hull would not show from the harbor. She was commissioned at Kure on 5 August 1942. Captain Kaoru Arima had her. She joined Battleship Division 1 with Yamato, Nagato, and Mutsu. She carried nine 18.1-inch guns.
On 11 February 1943, at Truk, she relieved Yamato as Admiral Isoroku Yamamoto's Combined Fleet flagship. Yamamoto left the ship on 3 April to direct the air operation at Rabaul. On 18 April he was killed over Bougainville. His ashes were brought back aboard on 23 April. Admiral Mineichi Koga took the Combined Fleet. On 17 May she left Truk for Japan with Kongo, Haruna, and that force, carrying the ashes. The Emperor visited her at Yokosuka on 24 June 1943.
Captain Keizo Komura took her on 9 June 1943. Captain Bunji Asakura took her on 6 December 1943. On 10 February 1944 she left Truk for Yokosuka with Admiral Koga embarked. She was the last Japanese battleship out of the lagoon before the February carrier raid. She carried stores and men on to Palau. On 29 March 1944, leaving Palau, USS Tunny hit her once in the port bow. The hole was about nineteen feet across. Seven men in the bow were killed. Eighteen men were casualties in all. She made 24 knots, reached Kure, and was repaired.
On 19 and 20 June 1944 she was with Yamato in Vice Admiral Takeo Kurita's force, ahead of the carriers, in the Philippine Sea. She fired at aircraft. She was not sunk. The submarine Cavalla (SS-244) sank Shokaku that day. That loss is not credited to Musashi.
Captain Toshihira Inoguchi took her on 12 August 1944. On 22 October she left Brunei with Kurita's center force, with Yamato, Nagato, Kongo, and Haruna. On 23 October, in Palawan Passage, the submarine Darter sank Atago and damaged Takao, and the submarine Dace sank Maya. Maya's survivors were put aboard Musashi that afternoon. Kurita moved his flag to Yamato.
On 24 October, in the Sibuyan Sea, aircraft from Task Force 38 hit the force through the day. The attacks are not credited to one carrier. Musashi took the weight of them. Her own record counts 19 torpedo hits and 17 bomb hits, and 20 near misses. Another account of the same fight says about twenty torpedoes and seventeen bombs. She was down by the bow. At 1936 she capsized, at 13-07 N, 122-32 E on her action report. The destroyer logs do not use that same point. Rear Admiral Inoguchi was lost. Of 2,399 men, 1,023 were lost. Kiyoshimo and Hamakaze took off 1,423 survivors, including her executive officer, Captain Kenkichi Kato. A decrypted message the next morning also counts men taken off by Isokaze. She was not off Samar on 25 October. She was struck from the Navy list on 31 August 1945.
