Ships
- IJN Nagato Captain from 2 August 1943
Mikio Hayakawa was born in Hiroshima Prefecture on 18 April 1894, the son of Hayakawa Kametaro. His elder brother was Kobayashi Seizo, who rose to full admiral. Hayakawa qualified for both the Naval Academy and the Army Academy and took the naval path. He graduated from Etajima on 22 November 1916 with the 44th class, 37th of 95, and began as a midshipman in the armored cruiser Yakumo. Training continued in the battlecruiser Haruna, the battleship Kawachi, the old cruiser Akashi, and the battleship Aki. He was commissioned ensign in December 1917 and lieutenant junior grade in December 1919, then passed through the basic torpedo and gunnery courses before serving in the destroyer Mikazuki, the battleship Yamashiro, and the seaplane carrier Wakamiya.
Torpedo work became his trade. After the advanced course he served in the second-class destroyer Karukaya and as torpedo officer of Nokaze, and from December 1925 he taught at the Torpedo School. He entered the Naval Staff College A course in December 1926, finished with the 26th class, and on 10 December 1928 became a lieutenant commander in command of the destroyer Tsuta. Staff billets with Battleship Division 3 and the Second Fleet alternated with more years of instruction, including a turn in the Navy Ministry education bureau. Promoted commander on 15 November 1934, he joined the Combined Fleet staff a year later.
On 1 December 1936 he was appointed aide to Prince Hiroyoshi of the Fushimi house, then commanding Destroyer Division 3. In the Shanghai fighting, on 25 September 1937, Chinese guns hit the division's destroyer Shimakaze in the Huangpu River, and Hayakawa was wounded with the prince. Shore duty at Yokosuka and a spell with the war-history section followed. In 1938 he held brief commands of the oiler Sunosaki and the seaplane carrier Notoro, and on 15 November he was promoted captain. He then led Destroyer Division 28 and, from November 1939, Destroyer Division 2 on the China coast. From 15 October 1940 he was chief instructor at the Torpedo School in Yokosuka, and he was still there when the Pacific War opened.
On 25 April 1942 he took command of the heavy cruiser Chokai in Nobutake Kondo's Second Fleet. The cruiser sailed for the Midway operation and stayed clear of the carrier battle. In July, Chokai became flagship of Gunichi Mikawa's Eighth Fleet and reached Rabaul at the end of the month, just as American troops landed on Guadalcanal. On the night of 8–9 August Hayakawa took Chokai at the head of the Japanese column into the fight off Savo Island. Allied heavy cruisers were sunk or left wrecked in the dark. Chokai took several hits, though a number of the shells failed to explode. With the transports off Lunga still in reach, Hayakawa urged Mikawa to turn back and strike them. Mikawa withdrew before daylight, weighing the risk of American carriers and of staying among ships that had already landed their troops. Through the autumn Hayakawa kept Chokai in the campaign, including the night bombardment of the airfield in mid-October and distant cover for the evacuation of Guadalcanal in early February 1943, then brought the cruiser home for refit.
On 1 March 1943 he moved to the battleship Yamashiro, employed mainly for training in home waters. On 11 June he was ordered to take the carrier Hiyo in tow after a submarine attack and was called off the same day once the cruiser Isuzu had reached her. On 2 August 1943, at Kure, he became captain of Nagato, relieving Yonejiro Hisamune. The battleship had been the Combined Fleet flagship of Isoroku Yamamoto at the start of the war, and Shinzo Onishi had commanded her in the year before Pearl Harbor. Hayakawa exercised the crew off Yashima, prepared the ship for a move south, and late in August took Nagato to Truk with a large part of the fleet. In September, after an American carrier raid in the Gilberts, and again in October, when the fleet sailed to head off an expected strike, he took Nagato out toward Eniwetok. Both sweeps ended back at Truk with the American forces unmet, and the battleship lay in the lagoon.
Promotion to rear admiral came on 1 November 1943, while he was still in Nagato. On 15 December he left the ship to command Destroyer Squadron 2 of the Second Fleet, and Yuji Kobe succeeded him. In the last year of the war the battleship passed to Kiyomi Shibuya and then to Miki Otsuka. Hayakawa hoisted his flag in the light cruiser Noshiro. Through the winter and spring his destroyers screened heavy ships as the fleet shifted away from Truk toward Palau, Japan, and the Lingga anchorage near Singapore, and they also covered ordinary traffic. At Tawi-Tawi in June 1944 an American submarine sank his destroyer Hayanami. When the fleet put to sea against the Marianas invasion he served in Takeo Kurita's vanguard at the Battle of the Philippine Sea, and on 20 June his ships joined the gunfire that met the American air strike in which the carrier Hiyo was lost.
After a refit in Japan he brought the squadron back to Lingga for combined training. In the Leyte operation of October 1944, Destroyer Squadron 2 screened Kurita's force on the run from Brunei through the Philippines. On 23 October, in the Palawan Passage, submarines sank the heavy cruisers Atago and Maya and damaged Takao. Hayakawa sent destroyers to the survivors, Kurita's staff among them, and detached others to stand by Takao. The next day, under air attack in the Sibuyan Sea, he ordered the damaged destroyer Kiyoshimo to take men off the battleship Musashi. Off Samar on 25 October, smoke, low cloud, and continual air attacks scattered the destroyers, and their torpedoes did little against the escort carriers. Noshiro landed shells on one of those carriers and was herself shaken by near misses and a hit. On the morning of 26 October a torpedo gutted Noshiro. Hayakawa transferred unhurt to the destroyer Hamanami, directed the rescue of the cruiser's crew, and went on to Brunei.
The remnant of the squadron was then committed to reinforcement runs from Manila to Leyte. He reached Manila early in November and on 4 November moved his flag to the large destroyer Shimakaze, a later ship of the same name as the destroyer on which he had been wounded in 1937. On 9 November he sailed with the third transport group for Ormoc Bay. On the morning of 11 November carrier aircraft caught the convoy in the bay and hit Shimakaze early. Hayakawa was killed aboard her. The destroyer burned for hours and then exploded and sank, and the convoy was wiped out aside from the destroyer Asashimo, which got back to Manila. The navy advanced him to vice admiral as of the day of his death. He was fifty years old.