Mikura class Escorts (1943)

Japan, 8 Escort (kaibōkan), 5 lost.

The Mikura-class escort ships were eight escort vessels built for the Imperial Japanese Navy, in parallel to the Etorofu and alternative design and the result on Destroyer tonnage limitations placed by the 1930 London Treaty. Officially they were called the “B-class” coastal defense vessel (乙型海防艦, Otsu-gata kaibōkan). If only eight were built versus 13 for the previous Etorofu, from Nihon Kōkan (5) and Hitachi Zōsen (3), built from late 1942 concurrently with later Etorofu-class. Five out of eight were sunk during the war.

(colorized by Irootko Jr)

Development

The Mikura-class, like the Chidori and Etorofu were consequences of the 1930 London Naval Treaty which limited the total IJN destroyer tonnage. It still be circumvented by using a loophole allowing ships of between 600 and 2,000 tons, with no more than four guns over 76mm, no torpedoes, and with a maximum speed of no more than 20 knots. Under 600 tonnes, this was free, including with any type of armament, and so Japan and Italy plunged into it for new classed of torpedo boats. Japan however, with the sad experience of its first class, and the Tomozuru affair (two classes were built in the interwar, the Tomozuru and Otori), looked at “improved guard ships” as dedicated patrol and ASW vessels, with the Shimushu class. The latter had been built by Mitsubishi on a specific in-house design and was found way too costly for what it was by the Imperial Japanese Naval Command. So a new class was requested as a much simplified version, the Etorofu class.

This new class of vessels were designed under the obsolete designation of kaibōkan (Kai = sea, ocean, Bo = defence, Kan = ship) previously used for obsolete battleships reassigned to coastal defense duties. But with the start of the Pacific War, the IJN saw the potential for a more anti-submarine warfare focused escort, so a parallel design to the Etorofu was worked on and through the 1941 Rapid Naval Armaments Supplement Programme were authorized eight “Type B” escorts, also better known as the Mikura-class. They were in essence, a simplified version of the Etorofu-class hull, with a better focus on ASW armament. The limited production was for “testing the waters” of this new design, for a possible future mass production.

Design of the class

Still, the Mikura shared a lot in common with the Etorofu class, as unlike the previous Shimushu design made by Mitsubishi Heavy Industries, optimized for operations in northern seas (areas potentially contested by USSR) tailored to deal with ice and heavy weathe, the newt “Type A-modified”, the Etorofu, had to keep a high freeboard, new hull shapes that were simplified, a more universal and simpler bow, long forecastle with a lot of flare no de-icing or heating systems and instead measired taken to “tropicalize” the design. Proof that Japanese engineers learned their lessons since the Tomozuru, they ad han excellent stability. The Mikura called “Type B” was further simplified, built with bulkheads without manhole and with a stern and bridge structure reworked and even further simplified.

Hull and general design

The Mikura class presented a much different appearance with a stepped bridge, smaller single smokestack replaced further aft, a new aft deckhouse, and new type of main gun. In size, they were very comparable, having the exact same hull as the Etorofu, measuring 77.7 meters (254 ft 11 in) overall, with a beam of 9.1 meters (29 ft 10 in) and a draft of 3.05 meters (10 ft 0 in). They displaced 960 metric tons (940 long tons) at standard load and 970 metric tons (955 long tons) at deep load, versus 870 long tons (884 t) for the Etorofu, so substantially larger.

Powerplant

The Mikura or Type B escorts were powered by two diesel engines, each driving its own propeller shaft, for a full rating of 4,400 brake horsepower (3,300 kW) and top speed of 19.5 knots (36.1 km/h; 22.4 mph). Range was good despite their small size, due to the use of diesels, at 5,000 nautical miles (9,300 km; 5,800 mi) at 16 knots (30 km/h; 18 mph) , meaning this could be extended even much further at 10 knots.

Armament

The Mikura differed a lot compared to the Etorofu class: Unlike the type A, armed with 120mm guns from scrapped old destroyers, the Mikura class had moder, dual-purpose guns of the same calibre, but in single and twin mounts. ASW armament was also much strengthened as seen above, with in addition a betetr suite with a 93-shiki sonar, and 93-shiki hydrophone. The Type 10 was installed in a single mount forward, as it was higher up on the forecastle and needed to be lighter to avoid topweight, and a twin mount aft on the lower deck and unshielded. The forward shield was mostly to guard against seawater spray. It was too thin to protected against 0.5 cal. rounds from US aircraft.

12 cm/45 10-shiki (Type 10) naval gun

Instead of the venerable 12 cm/45 first designed in 1895 as a derivative of the Elswick Ordnance Pattern Y. It was from 1921 redesigned as an high-angle AA gun, called the 12 cm/45 10th Year Type. It had a Single motion interrupted screw Welin breech block different from the Type 3 12 cm AA Gun used by the Army in 1943. On destroyers it was always shielded with the latter fitted with two opening panels. The ones fitted were not the 12 cm 11th Year Type naval gun (Model 1922) of TBs and the previous class, but the more advanced DP version found both on the Chidori and Etorofu class. It was said “dual-purpose” but in reality the mount limited them to 33° elevation only in the previous class, but this one might have the new HA mount that brought that elevation to 75° making for a maximum surface range of 22,430 yards (20,500 m) and a maximum AA Ceiling of 42,660 feet (13,000 m). Model 1922

⚙ specifications 12 cm/45 3rd Year

Weight 3,240 kg (7,140 lb), Barrel length 5.4 m (18 ft) bore
Elevation/Traverse -7° +75° and 120°/120°
Loading system: Welin breech block, Hydro-pneumatic recoil for 5–6 rpm
Muzzle velocity 825 m/s (2,710 ft/s), range 16 km (10 mi) at 33°
Crew: 6. Round 20.3 kg (45 lb) 120 x 550 mm.R., sep. loading cased charge

25 mm Type 96

These four Type 96 25-millimeter (1.0 in) anti-aircraft guns were planed in two twin-gun mounts abreast the bridge. The type 96 25 mm AT/AA gun became the standard of the IJA and IJN, automatic cannon developed as variant of the French Hotchkiss 25 mm, dual-purpose and developed as AA on single, twin and triple mounts. Development worked on 1935. 25 mm Hotchkiss design evaluated and order placed for several mounts types for evaluation at Yokosuka Naval Arsenal. Led to the Type 94 and Type 95 and then the main model produced at Yokosuka Arsenal, the Type 96. Elements made with castings and not forging for larger production, Rheinmetall supressor, new mounts designed. Air-cooled gas operated with multiple rings (Hotchkiss patent).

Twin-mount in 1939, followed by triple mount in 1941 and single mount in 1943. Issues of the designed revealed in combat:
Slow elevation and traverse, ineffective sights, excessive vibration, limited magazine cap., blinding Flashes.
The 1944 single mount needed a single operator and a loader but had a better spiderweb sight.

⚙ specifications 25 mm Type 96

Barrel Lenght 1.5 m (4 ft 11 in) L/60
Barrel weights: Single 785 kg (1,731 lb)
Barrel weights: Twin 1,100 kg (2,400 lb)
Barrel weights: Triple 1,800 kg (4,000 lb)
Crew: 3, 7 and 9 respectively
Shell 25×163mm
Exact caliber 25 mm (0.98 in)
Action Gas operated
Elevation/Traverse -10°/+85° – 360°, manual
Rate of fire 200–260 rpm (cyclic)
Muzzle velocity 820 m/s (2,700 ft/s)
Effective range 6.8 km (4.2 mi) at 45° with HE shell
Maximum firing range 85° 3 km (9,800 ft) effective, 5.5 km (18,000 ft) max.
Feed system 15-round box magazine

Depth Charges

The Mikura class were better armed against submarines, with still the same 81mm/12 Type 97 ASW mortar, but also no less than twelve Depht Charge Throwers for a grand total of 120 and a mechanical minesweeping gear. Initially these were Type 95 depth charges, with two Type 94 depth charge launchers.
Standard Type 95, 30.5″ by 17.7″ (77.5cm by 45cm). 220 lb (100 kg) charge, Type 88 explosive (ammonium perchlorate and ferrosilicate). Fuse using a water inlet. 100 feet (30m) and 200 feet (60m) settings (after the revelations of a US Congressman).
Later increased to 324 lb (147kg), Type 97 explosive (70% TNA/30% HNDA), 300 foot (90m) setting.
-1944 Type 2: 230 lbs (105kg) Type 97 explosive settings 98, 197, 292, 390, 480 feet (30m, 60m, 89m, 120m, and 145m).
-1945 Type 2: 357 lbs (162kg) explosives.

81mm Type 91 Mortar

A 15 cm (5.9″) ASW mortar was developed for transports and merchant ships in a cradle mounting that could fire a 60 lbs. (27 kg) charge at 4,500 yards (4,100 m) but it was too heavy for the esscorts, so instead, a modified Navy 81 mm mortar was carried by many escorts, firing standard projectiles. This modified version used by Imperial Japanese Navy with the designation Type 3 mortar was impromptu anti-submarine weapon designed for escort ships that was introduced in early 1943. This mortar was installed in front of the bridge and was some sort of “Japanese hedgehehog”.
The original Type 97 was a copy of the French Brandt mortar going back to 1936, produced from 1938 to the end of the war to 3892 units. It was fixed to the deck and weighted 66 kg (145 lb), but could fire at +85 degrees elevation a 6.5 kg (14 lb 5 oz) direct percussion charge at up to 1.2 km (0.75 mi). For longer range, they would use the Light HE: 3.3 kg (7 lb 4 oz) reaching 3 km (1.9 mi). Each of these were essentially grenades, to “clean up” the submarine deck from personal, especially gun crews. In theory it could also burst into the air or underwater at very short depth thanks to its delay pellet inserted in the fuze nose prior to firing.

Sensors

93-shiki (Type 93) sonar (1943)

2 kW 4400 lbs (2000 kg) model, FRQ 17.5 kHz, receiver gain 120 decibels 2, 4, or 8 seconds pulse interval, range up to 1640-3300-6600 yards (1500m-3000m-6000m) at 3°/10° resolution.
They also all kept their Type 93 Hydrophones in complement.

Type 22 Radar

The early Type 22 General Purpose Radar looks like characteristically like a 2910 lb (1320 kg) drum topped with a twin cornet amplificators, mounted mid-way top the mast.
Specs: Wavelength 10 cm, pwd 10 microsecond, PRF 2500 Hz, scan rate 5 rpm, PP 2 kW.
Range: 20 nautical miles (35 km) aircraft group, 10 nm (17 km) single, 13 nm(24 km) battleship.
Subject to land clutter. Horn and A scope display, accuracy 220 yards (200m)/3 degrees res. 1600 yards (1500 m)/40 degrees
300 sets produced installed on destroyers from the summer 1942. Generalized in 1944.

Type 13 Radar

Vertical 240 lb(110 kg) bedframe antenna, developed 1941, introduced mi-1943, with vertical dipole transmitter and Yagi mattress receiver. 1000 sets produced. Air defense, range 100 km (group), and single aircraft 50km. Specs: Wavelength 200 cm, pw 10 ms, PRF 500 Hz PP 10 kW, Range: 30-60 nautical miles (50-100 km).

Modernization

By late 1944, all surviving ships had their two twin 25mm/60 replaced by three triple 25mm/60 Type 96 and a single 25mm/60 Type 96, plus a Type 22 and a Type 13 radar also added, a third Type 94 depth charge launcher was added at the stern and the paravanes were removed. By early 1945, the last ships had their minesweeping gear removed and four single 25mm/60 Type 96 AA guns added, and by the time Japan surrendered, they all gained either two single or two twin 25mm/60 Type 96 more.

Production (list and builders)

Nihon Kōkan: #320 御蔵 Mikura, #322 三宅 Miyake, #327 倉橋 Kurahashi, #329 千振 Chiburi, #334 草垣 Kusagaki
Hitachi Zōsen: #324 淡路 Awaji, #326 能美 Nōmi, #331 屋代 Yashiro.

-14 of the above ships were completed to the Etorofu design with modifications
-8: Mikura (#320), Miyake (#322), Awaji (#324), Nōmi (#326), Kurahashi (#327), Chiburi (#329), Yashiro (#331) and Kusagaki (#334) were altered as the Mikura design
-3: Hiburi (#328), Daitō (#333) and Shōnan (#339) were altered to the Hiburi design
-5: Ukuru (#332), Okinawa (#335), Amami (#336), Aguni (#337) and Shinnan (#338) were altered to the Ukuru design.

Mikura class, Author’s old profile.

⚙ Mikura class specifications
Displacement	940t standard, 1020t FL
Dimensions	77.7 x 9.1 x 3.05 m (255 ft x 29 ft 10 in x 10 ft)
Propulsion	2 shafts geared Kampon diesel (4,200 bhp)
Speed	19.7 knots (22.7 mph; 36.5 km/h)
Range	5,000 nautical miles at 16 knots
Armament	Twin 120m/45 Type 10, 1x 120mm/45, 2×2 25mm/60 Type 96, 1x 81mm/12 ASW mortar, 12 DCT (120), sweeping gear
Sensors	Type 22 radar and Type 93 sonar
Crew	150 (1945)

All eight saw heavy combat service, in the South China Sea and East China Sea, as used for convoy escort. Two US submarines *may have* being sunk, one by Chiburi (USS Growler on 8 November 1944) and Mikura (USS Trigger on March 28, 1945). Five were lost, four to USN submarines however so the USN had a 1/2 advantage on the very ships hunting them. A single ship survived the war in a state good enough to be used for repatriation duties after being disarmed and given as a was reparations to the Republic of China Navy, in service until 1963 (see below).

IJN Mikura (御蔵)

御蔵 Mikura was ordered from Tsurumi, Yokohama, laid down on 10.1942, launched on 16.7.1943 and commissioned on 10.1943. On 14-27 November 1943, she escorted the 3114 convoy (Takebe Maru and Daido Maru) from Yokosuka to Truk. On the 15th, the 2nd Maritime Escort Flotilla was subordinated to the Maritime Escort General HQ. On 5 December, she escorted the 4205 convoy (Akihayama Maru and Soyo Maru) with Hirado from truk to Yokosuka but on the 7th, she assisted Soyo Maru, sunk by USS Pogy. Mikura escorted Akihayama Maru to Saipan. Next she escorted the 4205 convoy with Satsuma Maru at Saipan, departed for Japan on the 12th, attacked off Iwo Jima, and colliding with a transport ship (light damage). They arrived at Yokosuka on the 20th.
From 4 January to 8 February 1944 she was docked at Nippon Kokan Asano Shipyard, making a round trip to Yokosuka. On 11 February, she escorted the fleet from Yokosuka to Saipan on the 19th, departed on the 27th to Truk and on 5 March, arrived, then a day later departed back to Japan via Saipan, arriving on the 19th.

On 1 April, Mikura escorted the Higashimatsu No. 4 fleet from Kisarazu, via Saipan on the 9th. She was reassigned to the 2nd Maritime Escort Flotilla, and proceeded to Truk. On the 12th she detected and attacked a target, which escaped. She was in Truk on the 15th and on the 22nd, she departed for Japan. On the 26th she arrived at the relay station Saipan and Yokosuka on 4 May. She departed from Yokosuka on 15 May, for Saipan/Palau and stopped at the relay station Saipan, followed by ASW alert off Saipan. On the 30th she escorted the fleet to Palau, arrived on 6 June. 6 days later she escorted the fleet for Saipan, but this was changed to Davao after a US air raid on Saipan. She learned she was under command of the 1st Maritime Escort Flotilla and on the 20th, escorted the fleet to the gusset and Davao on the 22nd. On the 30th, she was sent to join the Seda 01 fleet, back to Davao on 3 July, departing on 6 July escorting the Dama 01 fleet to Manila (13th) and 2 days later, escorted the Mi 08 fleet from Manila, but turned back (typhoon). On the 17th she escorted the Tama 21C fleet and joined the Hi-69 fleet under the 1st Maritime Escort Corps. She returned to Manila on the 20th and 3 days later escorted the Hi-68 fleet for Japan, but stopped at Kaohsiung (28th) arrived on 3 August.

She entered Sasebo on 4 August for maintenance until the 7th, sailed to Imari and on the 10th, escorted the Hi-71 fleet to Magong (bad weather) and a day later, had a submarine attack, they arroved at San Fernando on the 19th. A day later she was involved in ASW sweeping with aircraft. She entered Manila on the 21st and 5 days later, escorted the Hi-71 fleet for Manila and arrived in Singapore on 1 September. On 6 September, she escorted the Hi-72 fleet from Singapore attacked underway on the 12th (2 transports, Shikinami and Hirado sunk). Mikura rescued Shikinami’s crew after her depth charge attacks. On the 13th, they sailed to Narabayashi but she returned for more rescue. On the 16th, she escorted part of Hi-72 Fleet (Asaka Maru) to Sasebo. On the night of the 20th, bith were attacked and damaged USAAC aviation in the Taiwan Strait. Asaka Maru took a direct hit an near-misses. She was later escorted to Iturup and Magong, docked and repaired.

On 6 March and the 9th, Mikura made an ASW sweep with two other escorts and rescued the crew of another damaged with the Yumo 01 fleet. On the 13th, she proceeded to Hong Kong, but bad weather marred Operation AS2. She was in Moji on the 26th and joined the 2nd Fleet, 1st Squadron, training in Saeki with Oga, Meto, 2 more escorts and 3 “special minesweepers”. They received a sub-chaser from the Saiki Defense Force and an aircraft of the Saiki Air Corps with a magnetic detector. They developed together a new point and patrol method on the 27th and sailed for Moji, then Saeki. The 3rd ASW Squadron fixed the course south, beyond the Mizunokojima Lighthouse for a search. They took a single horizontal formation, 4 nautical miles long, 3 nautical miles wide, with Mikura on the westernmost side. At 10:27 am, the aircraft detected a submarine, but soon lost sight. Around midnight, they detected the sub, 1,000 meters west on escort in a single line, rushing for better detection. They depth charge attacked around 13:00, and observed two large water plumes of explosions, reported by Tsurumisaki. On 29 March, a thick oil slick was observed? Postwar records accorded this to be USS Trigger.

Later the same day, news south of Kyushu signalled a large air raid and one escort sunk by a torpedo attack from USS Threadfi. At 16:45, another escort discovered and reported and aircraft, but Threadfin sank Mikura there according to US records, albeit it conflicts with the sinking position of No. 33 Kaibokan (Name ?) in The Official Chronology of the US Navy. It was attributed later to an USS Hornet aircraft. Short story, this is still disputed today. But the result was the same: Under captain Major Ryusuke Oda, 171 crew members killed in action, no survivors. On 25 May, she was stricken from the Imperial Kaibokan (register).

IJN Miyake 三宅

Miyake was laid down at Tsurumi, Yokohama on 2.1943, launched on 30.8.1943 and commissioned on 11.1943. She was homeported in Kure Naval District. She operated under the CiC Maritime Escort General HQ Koshiro Oikawa, Admiral on 15 November. She joined the 1st Maritime Escort Flotilla. She departed Yokosuka with the 2705 fleet on 5-7 December to Kure for training and from 21 December started an escort mission with 123rd Fleet from Moji to Kaohsiung with nine transports. On 27 December they were joined by the Etorofu-class Matsuwa and sailed to Singapore. The tanker Kueimaru was the only loss (submarine). Miyake was back in Kaohsiung on the 29th. From 20 January, with an Etorofu-class escort she escorted the Hi-37 fleet from Moji, via Manila, to Singapore. In cover were the light aircraft carrier Chitose (3rd CarDiv) and the 16th DesFlot. Amatsukaze and Yukikaze (3rd Fleet, Ozawa). She was in the 3rd Carrier Division to Singapore. On 16 January Amatsukaze was sunk by USS Redfin. On 20 January, the Hi-31 fleet arrived in Singapore and back was renamed the Hi-32 fleet on 25 January. Miyake remained in Manila until the 27th and joined Hi-32 and 4-5 February, to Kitakyushu and Kure.

After maintenance in Kure, Miyake was ordered to Moji. On 16 February, she escorted the tankers Kuroshio Maru, Tamatsu Maru, and Tatekawa Maru (Hi-45 fleet) along with f 7 transports (10,090 tons) with Shiokaze from Moji and on 19 February, to Kaohsiung when attacked by USS Jack. Shiokaze was sent in hunt. On the 21st, the Hi-45 fleet arrived in Kaohsiung, Miyake warned about a sub presence off Kaohsiung and in the night, Miyake moved to Zuoying. On the 22nd she departed Kaohsiung with the TB Hayabusa. Miyake left Zuoying and joined in, escorted the tanker Kuroshio Maru which had an engine failure, sent to Kaohsiung. On the 23rd, Tamatsu Maru separated with Hayabusa for Manila. Shiokaze joined the Hi-40 fleet. The convit arrived on the 27th in Singapore.
4-5 March saw Miyake with the Hi-47 fleet (Etorofu and Iki) when attacked by USS Bluefish. Omineyama Maru was sunk. On 11 March, 4 escort ships (Miyake, Shimushu, Iki, and Etorofu) departed Singapore with Hi-48 fleet but at 01:00 am on 18 March, Hokuriku Maru was sunk by USS Rapon, men were rescued. They stopped at Kaohsiung, and returned to Moji on 25 March.
On 30 March, Miyake and Manju were attached to the Combined Fleet and on 28 May, escorted Ashizuri and Zuiho. On 5 June, USS Puffer attacked the oil tanker fleet in the Sulu Sea and Ashizuri and Zuihō were sunk.

On the 18th, Operation Sho-go was launched, and the Kurita Squadron and 2nd Squadron (cdr. Kiyohide Shima CiC 5th Fleet or Shima Fleet) mixing Army and Navy assets, were confused over the arrangement of tankers. Vice Admiral Kurita was forced to secure tankers, ordering Niei Maru and Ryoei Maru to wait for Sanya, Hainan Island. 4 tankers (Niei Maru, Ryoei Maru, Kuroshio Maru, Toho Maru) joined the Hi-76 fleet to supply troops with Miyake and Manju in escort of Ryoei Maru to Penghu Island, Mako. On the 20th at 09:30 they arrived at Mako to replenish the 2nd Squadron but on the 22nd at 07:00 a new escort force was mounted (Kurahashi, Miyake, Manju) to escoort the tankers Niei Maru and Ryoei Maru, leaving on 23 Octobe to Xiamen City, opposite Taiwan on the 26th. On the 29th, under Captain Kagayama (Miyake’s CO) Miyake she departed while escorting a repair ship to Brunei, Borneo, later to Singapore. By 20 November, the 31st Squadron entered the 5th Fleet (Lt. Gen. Kiyohide Shima CiC, flagship Ashigara) annd witnessed the Battle of Ormoc Bay. This 30 December air raid basly damaged one escort and sank the Aobayama Maru, Miyake was unscathed.

On 9 January 1945 she was in Kaohsiung, Taiwan, to join the Hi-87 Convoy (General Katsumi Komazawa, Flagship seaplane tender Kamoi) with Shigure, Isokaze, Hatakaze, tankers, Mikura and Kurahashi, eight other ships. They were attacked by TF38 aircraft and Kamoi and Yashiro were damaged, Kaihomaru sunk. Miyake left Kaohsiung on 10 January with the Hi-87 fleet for Hong Kong. They were also caught by an air raid while in Hong Kong. Noumi and Kurahashi were damaged. On 19 March, Kure was attacked. In mid-April, 4 escorts under command of Captain Ei Ikeda, 1st Escort Flotilla (Noumi, No. 31, Miyake, No. 213) escorted the Moshi 02 fleet (Kotobukiyama Maru, Dalian Kisen) from Monji on 11 April for Jeju Island on 13 April. On 14th at dawn they were attacked by USS Tirante while moored inside the harbor. Kotobukiyama Maru, Nomi, and aother escort were sunk. On 18 April, Miyake returned to Moji. On 22 April, she escorted Jilin Maru, left Moji but mines were a danger and Miyake patrolled between Jeju Island and Tsushima. She was off Qingdao on 8 May, then Ishijima on 17 May, and joined the Daiseimaru fleet at Daito Bay on the 21st. On 22-24 she escorted Koyo Maru to Ishijima and took part in the land battle, called for shelling. On 25 May, she left Ishijima with Tatsumiya Maru and Okitsu Maru for Daito Bay (26th). In June, she entered Sasebo, left on 1 August for the Yobuko fishing port, and from there, Wonsan, Korean on 7 August. She left Motoyama on the 10th, moved to Yeongil Bay when strucking a mine and being badly damaged near Moji (Kitakyushu) on 21 August. Never repaired she was refitted enough to act as auxiliary ship until sod for BU and scrammed at Sasebo from May to July 1948.

IJN Awaji (淡路)

Awaji was ordered from Hitachi, Sakurajima and laid down on 6.1943, launched on 30.10.1943 and completed on 2.1944. On March 24, she teamed up with sub-chaser N°19 and gunship Beijing Maru from Kaohsiung to escort the Tasa-31 fleet convoy (16 ships) to Vietnam on April 1. On the night of April 4, IJN Awaji left Sanjak on a single engine after a breakdown and moved to Singapore. From the 8th to the 27th her diesel was under repair by the 101st Navy Engineering Department in Singapore. She left to join the Simi 01 fleet on the 28th, arrived in Miri, Borneo and on May 4, escorted 02 fleet (17 ships) from Miri and at 8 am on May 6, she sank USS Crevalle. The convoy arrived in Manila on May 10, departed 3 days later to Mutsure, Kitakyushu on the 23rd, via Kaohsiung. She herself sailed to Sasebo, to have her new sonar installed. In late May she escorted the Hi-65 convoy to Singapore under the 7th Convoy Command (Maj. Gen. Mitsuharu Matsuyama) from the flagship Kashii: 10 ships, includ. Shinshu Maru, escorted by the Taiyo-class aircraft carrier Kaiyo, Awaji, Chiburi, No.19, Sub-Chaser No.60, and Tsubame. On May 29, they departed from Moji but while off the eastern coast of Taiwan, they entered a deep rain squall and after 2:00 am on June 2 ambushed by USS Guitarro (6 torpedoes on a tanker). Awaji spotted the torpedo trails, reported them to the flagship. Hi-65 started to disperse but Awaji was hit, and only 5 were rescued (Capt. Kozo Niki and the rest of the crew went down under) by escort No.19, others by Chishin. On July 10, Awaji was stricken.

IJN Nomi (能美)

IJN Nomi was laid down at Tsurumi, Yokohama on 8.1943, launched on 3.12.1943 and commissioned on 3.1944. On June 23, Nōmi left the Yokosuka Naval District and Maritime Escort Flottila to place herself under command of Ominato Guard (Lt. Gen. Yasuo Inoue) and the military division maritime escort unit, Soya Defense Force. On the 27th, Nōmi arrived in Ominato, Aomori Prefecture and a day after transferred to the Soya Defense Force (Captain Tsuguo Chiba) with No. 15 sub-chaser and sailed to Wakkanai, northern Hokkaido, on the 30th. She started escorting convoys for the Northeast Area Fleet, including rescue missions in the Sakhalin, Kuril Islands, Hokkaido. Since the 2nd Maritime Escort Flotilla HQ was then at Saipan, it was wiped out, and her unit disbanded. On September 5, Nōmi and Namikaze escorted the Ki-505 convoy from Otaru but on the 8th, Namikaze was sunk by USS Seal and Nōmi pressed ASW search. The Ominato Guard Office dispatched Nokaze to rescue Namikaze and Kokugo Kaibo in escort, albeit the convoy remained in between unprotected. Namikaze was towed by the destroyer IJN Kamikaze, and was escorted by Nokaze, Hachijo and Fukue to Otaru. On September 9, USS Seal found the Ki-505 convoy, torpedoed the Shonan Maru. On the 10th, Nōmi looked for Shonan Maru, but she couldn’t find any survivors. The convoy had lost her escort, and was evacuated to Sakhalin Kaori. Nōmi and Kunashiri also sailed there. Nōmi housed survivors of Shonan Maru in betwee, which escaped on rescue boats. On the 15th, Nōmi and Kunigo resumed escort the Ki-505 convoy to Shiki, Paramushir Island and Kataoka Bay on the 22nd. On the 24th, she escorted the convoy 403 from Kataoka Bay. USS Searaven operating close, sunk the transport Riyama Maru.

On the morning of the 26th, the convoy 403 was escorted by Kunigo and Nōmi, dispersed in thick fog and Nōmi lost them. From midnight to early dawn, 27th, Nōmi detected and chased a submarine north of Etorofu Island, apparently the latter was surfaced when she spotted her directly and a fight started, but the unknown submarine was heavily armed and Bofors, Oerlikon and her main 5-in gun managed to kille 7 and injuring 16 on the escrt. Breaking the fight, Nomi had to sail to Ominato for emergency repairs via Otaru on the 29th. On December 4-1, she was in maintenance and magnetic degaussing at Sasebo Naval Arsenal. On the 10th her unit was reorganized so she entered the 1st Escort Flotilla (Fukuji Kishi). On the 12th she was selected to escort the Mota-28 Convoy (Nōmi, Miyake, No.20, No.112, No.138, and 2 more) from Sasebo and on the 22nd, they arrived in Kaohsiung in Taiwan. On the 25th she was assigned to the Hi-85 convoy (commander Maj. Gen. Shibuya Shibuya) arrived in Kaohsiung, and both fleets were reorganized. 26th 09:00, Tama-38 Fleet Unit (Miyake, Nōmi, No. 20, No. 39, No. 112, No. 138, Shinshu Maru, Kibitsu Maru, Aobayama Maru, Hinata Maru) from Kaohsiung to San Fernando, Luzon. Aobayama Maru and the No.20 Kaibokan were damaged in an air attack but the landing was successful.
1945

On February 1-4, 1945, Nomi escorted another convoy to Saigon, and departed on the 5th, transferred to the 1st Escort Flotilla, 1st Escort Fleet to Singapore on the 6th. She left on the 11th, escorting with the 88F convoy, through Quinone Bay and Tourane via Hong Kong and tasked to repair Nōmi. On the 26th her repairs were completed, she departed from Hong Kong to Moji on March 8. She later had repairs and maintenance plus modernization at Kure, notably receiving the new Type 3 Depth Charge Projector, and No. 1 radio wave detector type 3 Kaiichi. She became so flagship of the 1st Escort Flotilla on March 20, Captain Akira Ikeda, Commander, Sea Defense Corps. Ready by April 2 she departed for Moji and on the 11th, with Miyake, No.31, she escorted the Moshi-02 (special transport ship Toyama Maru, 3,943 tons, 400 passengers from Moji. On 13th they arrived at Jeju Island. Umi entered the escort force, taking turns on patrol. Before dawn on the 14th they were attacked by USS Tirante which managed to enter the harbor and torpedoed the Toyama Maru. Nōmi chased Tirante, but one of her next torpedoes hit directly Nōmi under the keel at the bridge’s height. Her ammunition detonated she broke in two and sank with 130 crew members, inc. Colonel Ei Ikeda (1st Escort Flotilla), Major Saburo Agen, captain, Escort group. Tirante fired her last torpedo at the escort No. 31, a dud, but the impact triggered a depth charge. She detonated, capsized and sank (39 killed). Miyake and Aguni, No.39 made a sweep, but failed to detect her. On May 25, Nōmi was stricken.

IJN Kurahashi (倉橋)

Kurahashi was ordered from Tsurumi, Yokohama, laid down on 6.1943, launched on 15.10.1943 and completed on 3.1944. On March 10, she left the Kure Defense Squadron for the 1st Maritime Escort Flotilla, to defend the southwestern sea lanes, under the Maritime Escort General Command. Sine the recent carrier IJN Kaiyo just received the Type 97 B5N “Kate” in ASW version with the 93rd Navy Air Corps, she trained with her in Saiki, Kyushu on the 11th to the 16th. Kaiyō was then transferred to the 1st Maritime Escort Flotilla on March 17 and stayed with Kurahashi, sailing for Kure and on the 21st departed for Moji. On the 23rd, she escorted the Mota-13 convoy (12 ships) with the sub-chaser N°26, out of Moji and to Kaohsiung, Taiwan on the 30th. From August 5, Hirado, Kurahashi, and Mikura remained at Sasebo in maintenancebefore sailing to Imari to join the Hi-71 convoy, departing with Otaka, Fujinami, Yunagi, Hirado, Kurahashi, Mikura, Shonan under command of General Kajioka Sadamichi, 6th escort fleet. The cargo ships were Irago and about 20 others from Imari. One ship had a breakdown, and took refuge at Penghu Islands. Asakaze and four escorts, Sado, Matsuwa, Etorofu, Nisshin joined the convoy and on the 17th, Hi-71 left Magong for Manila. From the 18th to the 19th, the USN had several wolfpacks in the area, with eight submarines such as USS Flasher in the area. They attacked from multiple directions, eight ships were hit by torpedoes, including Otaka. Five sank. Kurahashi escorted Nissho Maru, separated from the fleet, to Manila on the 21st. Sado, Matsuwa, and Nisshin, separated from the convoy for ASW sweeping, were also sunk by USS Harder and USS Haddo on the 22nd off Manila.

With the Hi-68 convoy in Manila, Major General Yoshitomi, 5th escort fleet commander of the flagship Kashii plus three light aircraft carriers of the army, carried reinefocement IJA aircraft to the southwest. The “Moma-Convoy” (Monji-Manila) and Otaka completed the aircraft transport mission with Hi-69 and fused with Hi-68. On the 23rd, Hi-68 (16 ships inc. Hirado, Kurahashi, Mikura, Kusagaki, and Otaka) left Manila and on the 25th-26th, while underway to Kaohsiung, they were ambushed by USS Angler, USS Flasher, and USS Crevalle from the same wolfpack and attacking in succession: The idea was the first would draw out the escorts, leaving the convoy unprotected for the next. Four ships were sunk. Kurahashi rescued men of the Aki Maru after dropping depht charges. After entering Kaohsiung, there was a reorganiztion. Hirado, Kurahashi, Mikura continued to escort Hi-68 fleet from Kaohsiung to the coast of Rokuren and Moji on August 3.

January 6-7 1945, saw the Hi-87 convoy gathered off Keelung, Taiwan and at 11:25 am on the 7th, the Army cargo Sozo Maru was damaged by a torpedo from USS Picuda. The convoy sailed to Kaohsiung, under command of 17th Destroyer Squadron, Sozomaru guard. Kurahashi escorted Munakata Maru all teh way. The 17th Destroyer Flotilla (Hamakaze and Isokaze) then joined th carrier IJN Ryuho to Keelung, joining then Sozomaru and Kurahashi. Sozomaru was escorted by Hamakaze, Isokaze, and Kurahashi and arrived at Keelung. Hamakaze and Isokaze returned to escort the convoy with Kurahashi ordered back to Kaohsiung. On the 9th, the conviy Hi-87 Farrived in Kaohsiung, only to be attacked by carrier-based aircraft from TF38. On February 3, she escorted the Tamo-40 convoy. On February 5, she sailed to Sasebo for maintenance in drydock on Feruary 13 to 5 March. She then joined Hi-88F, sailing to the Lighthouse of Hikoshima and to the northern end of Tsushima on the 8th. She made six escorts of that sort and on the 14th, escorted Mota-42 (2 ships) six times via Daicho Kanayama and Daihoku to Keelung on the 27th. On the 31st she escorted Tamo-52 fleet to Keelung. Next she patrolled on the southern coast of the Korea. However by that stage fuel was scarce a,d she ended interned at Motoyama until August 15. Thay day she sailed for Ominato. On the 25th, she was under the Yokosuka Naval District First Reserve. She was used as minesweeper off Muroran from September 15th, stricken on November 30, after the Ministry of the Navy was disbanded. On December 1 under the 2nd Ministry of Demobilization, she became a minesweeper for the local demobilization Ominato district force.

By March 1946, Yashiro, No. 48, No. 49, No. 77, escorted by USS Shoveler and USS Redstart were minesweeping off Kikaijima and Amami Oshima. On September 1, she was converted to an auxiliary ship for the Ominato District Demobilization Group, then “special storage ship”, Yokosuka Special Storage Ship No. 4 Storage Group. On March 31, 1947, with her local Demobilization Bureau disbanded, she passed under the Yokosuka District Demobilization Bureau. On September 4, she was handed over to Britain as war reparation on the 14th, then sold for BU at the Nagoya dock on January 15, 1948.

IJN Chiburi (千振)

Chiburi was laid down at Tsurumi, Yokohama on 7.1943, launched on 30.11.1943 and commissioned 5.1944.

IJN Yashiro (屋代)

Yashiro was laid down Hitachi in Sakurajima 11.1943, launched 16.2.1944 completed 6.1944.

IJN Kusagaki (草垣)

Kusagaki was laid down Tsurumi, Yokohama 9.1943, launched 12.1.1944, completed 7.1944.