(GENKAI MARU, similar to KOKAI MARU except for counter stern, seen prewar)*

Tabular Record of Movement

© 2013-2014 Gilbert Casse, Bob Hackett and Peter Cundall

Revision 1

May 1938:
Hakodate, Hokkaido. Laid down by Hakodate Dock K.K. shipyard for Shimatani Kisen K.K. as a 3,871-tons cargo ship.

January 1939:
Launched and named KOKAI MARU. [1]

May 1939:
Completed and registered in Kobe.

3 October 1941:
Requisitioned by the IJN.

10 November 1941:
Registered in the IJN as an auxiliary transport, (Otsu) category and attached to the Maizuru Naval District with Maizuru as homeport under internal order No. 1391. Assigned that same day to transport the 7th Construction Unit to Truk. [2]

16 December 1941:
Departs Tokyo.

5 January 1942:
Arrives at Truk, Central Carolines.

6 January 1942:
Tactically assigned to “R” Operation (Invasions of Rabaul and Kavieng) Seizure Force.

17 January 1942:
Vice Admiral (Admiral, posthumously) Nagumo Chuichi’s (36) Carrier Striking Force departs Truk consisting of CarDiv 1’s AKAGI and KAGA, CruDiv 5’s SHOKAKU and ZUIKAKU, BatDiv 3/1 HIEI and KIRISHIMA, CruDiv 8’s TONE and CHIKUMA and DesRon 1’s light cruiser ABUKUMA with DesDiv 17's ISOKAZE, URAKAZE, TANIKAZE, HAMAKAZE, DesDiv 18's ARARE, KASUMI, KAGERO, SHIRANUHI and unattached AKIGUMO.

20 January 1942: - Operation "R" - The Invasions of Rabaul and Kavieng:
N of New Ireland. CarDivs 1 and 5 launch 100 bombers and fighters to attack Rabaul, New Britain and Kavieng, New Ireland. That evening, CarDiv 5 is detached and moves to a position in the Bismarck Sea.

21 January 1942:
CarDiv 1 launches another strike on Rabaul and CarDiv 5 launches attacks on Madang, Lae and Salamaua, New Guinea. After CarDiv 5 recovers her aircraft, she departs the Bismarck Sea area that evening to rendezvous with CarDiv 1.

22 January 1942:
CarDiv 1 launches a 45-plane strike against Rabaul. After the launch, CarDiv 5 rendezvouses with CarDiv 1. When CarDiv 1 completes recovery of her strike aircraft, Nagumo heads north to Truk.

That same day, Rear Admiral (later Vice Admiral) Shima Kiyohide’s (39) invasion forces arrive in Rabaul waters. The main body consists of: Rear Admiral (Vice Admiral posthumously) Goto Aritomo’s (38) Screening Force CruDiv 6’s heavy cruisers AOBA, FURUTAKA, KAKO and KINUGASA, and seaplane tender CHITOSE providing air cover.

Rear Admiral (Vice Admiral posthumously) Kajioka Sasamichi’s (39) Seizure Force consisting of auxiliary aircraft transport MOGAMIGAWA MARU and Mine Division 19's TSUGARU, OKINOSHIMA and auxiliary minelayers TENYO MARU and TOKIWA with DesRon 6's YUBARI, DesDiv 30's MUTSUKI, MOCHIZUKI, YAYOI, DesDiv 29's OITE, ASANAGI and YUNAGI. Other escorts are G-Btdiv5 consisting of NIKKAI and SEIKAI MARUs and SC-DIV 56’s auxiliary subchasers TOSHI MARU No. 5 and TAMA MARU No. 8 escorting the Transport Group consisting of auxiliary transports KOKAI and KOZUI MARUs, auxiliary merchant cruiser KONGO MARU and auxiliary seaplane tender KIYOKAWA MARU. They carry the 4th Ammunition Unit, the 2/2 Maizuru Special Naval Landing Force (SLNF), the 7th Construction Unit and the 5th Base Unit including an AA unit.

22/23 January 1942:
Soon after midnight, minelayer OKINOSHIMA lands invasion troops at Blanche Bay, Rabaul. The invasion forces swiftly overcome light Australian opposition and occupy both Rabaul and Kavieng.

1 February 1942:
Tactically assigned to “R” Base Force.

20 February 1942:
Tactically assigned to “SR” Operation to transport SNLF troops in New Guinea.

5 March 1942: Operation “SR” – The Invasions of Lae and Salamaua, New Guinea:
Rear Admiral (later Vice Admiral) Shima Kiyohide’s (39) Invasion force departs Rabaul for Lae/Salamaua, New Guinea consisting of:

Rear Admiral (Vice Admiral posthumously) Kajioka Sadamichi’s (39) Seizure Force DesRon 6 light cruiser YUBARI, DesDiv 30’s destroyers MUTSUKI, YAYOI and MOCHIZUKI, minelayers TSUGARU (F) and OKINOSHIMA, seaplane tender KIYOKAWA MARU providing air cover, MinDiv 14 auxiliary minesweepers HAGOROMO and TAMA MARUs, NOSHIRO MARU No. 2 and TAMA MARU No. 2, auxiliary transport KOKAI MARU, auxiliary minelayer TENYO MARU, auxiliary merchant cruisers KINRYU and KONGO MARUs, those four ships carrying the 2nd Maizuru SNLF to Lae and IJA transports YOKOHAMA and CHINA MARUs carrying the 2/144 Regiment to Salamaua.

Rear Admiral (later Vice Admiral) Marumo Kunimori’s (40) Close Cover Force CruDiv 18’s light cruisers TENRYU and TATSUTA and DesDiv 29’s destroyers YUNAGI, ASANAGI and OITE.

Rear Admiral (Vice Admiral posthumously) Goto Aritomo’s (38) Distant Force CruDiv 6’s heavy cruisers AOBA, FURUTAKA, KAKO and KINUGASA and DesDiv 23’s destroyers YUZUKI, UZUKI and KIKUZUKI.

8 March 1942:
The Invasion force arrives at Lae and Salamaua and proceeds to the landings without opposition.

10 March 1942:
Off Lae and Salamaua. The Invasion force is attacked by Vice Admiral Wilson Brown (USNA ’02) Jr. Task Force 11, including ships of Rear Admiral (later Admiral) Frank J. Fletcher's (USNA ’06) TF 17. Ninety aircraft (SBDs, TBDs and F4Fs) of USS LEXINGTON (CV-2) and YORKTOWN (CV-5) fly over New Guinea' s Owen Stanley mountain range from the Coral Sea to make the attack.

Armed merchant cruiser KONGO MARU (casualties unknown), auxiliary minelayer TENYO MARU (nine crew KIA) and transport YOKOHAMA MARU (one crew KIA) are sunk. KOKAI MARU, minelayers OKINOSHIMA and TSUGARU, light cruiser YUBARI, destroyers YUNAGI, ASANAGI, OITE, seaplane carrier KIYOKAWA MARU, minesweeper W-2 and TAMA MARU are damaged.

E March-April 1942:
Undergoes emergency repairs at Truk.

23 April 1942:
Arrives at Maizuru.

24 April 1942:
Assigned to transport 43 people to the South Seas District (Japanese mandated islands).

15 May 1942:
Removed from the Navy’s list under internal order No. 852.

April-October 1942:
Under repairs.

10 October 1942:
Repairs are nearly completed. Scheduled to be de-requisitioned.

20 October 1942:
Repairs are completed.

24 October 1942:
Released to her owners.

25 October 1942:
Departs Maizuru.

1 November 1942:
Arrives at Chingwangtao, (Quinhuandao), northern China. Departs later that day for Kenjiho, Chosen (now North Korea).

2 November 1942:
Arrives at Kenjiho.

6 November 1942:
Departs Kenjiho.

8 November 1942:
Arrives at Dairen, Manchuria (now Dalian, northern China).

11 November 1942:
Departs Dairen.

17 November 1942:
Arrives at Muroran, Hokkaido.

23 November 1942:
Departs Muroran and arrives later that day at Hakodate.

26 November 1942:
Departs Hakodate.

27 November 1942:
Arrives at Otaru, Hokkaido.

2 December 1942:
Departs Otaru.

9 December 1942:
Arrives at Jinsen, Chosen (now Incheon, South Korea).

11 December 1942:
Departs Jinsen.

12 December 1942:
Arrives at Dairen.

17 December 1942:
Departs Dairen.

23 December 1942:
Arrives at Otaru.

2 January 1943:
Departs Otaru.

4 January 1943:
Arrives at Hakodate.

5 January 1943:
Departs Hakodate.

10 January 1943:
Arrives at Jinsen.

14 January 1943:
Departs Jinsen.

15 January 1943:
Arrives at Dairen.

19 January 1943:
Departs Dairen.

24 January 1943:
Arrives at Fushiki, Toyama Prefecture.

26 January 1943:
Departs Fushiki.

27 January 1943:
Arrives at Niigata.

31 January 1943:
Departs Niigata.

5 February 1943:
Arrives at Dairen.

12 February 1943:
Departs Dairen.

17 February 1943:
Arrives at Fushiki.

19 February 1943:
Departs Fushiki.

20 February 1943:
Arrives at Niigata.

22 February 1943:
Departs Niigata.

23 February 1943:
Arrives back at Niigata.

27 February 1943:
Departs Niigata again.

4 March 1943:
Arrives at Dairen.

8 March 1943:
Departs Dairen.

12 March 1943:
Arrives at Fushiki.

13 March 1943:
Departs Fushiki.

14 March 1943:
Arrives at Niigata.

16 March 1943:
Departs Niigata.

18 March 1943:
Arrives at Otaru.

20 March 1943:
Departs Otaru.

21 March 1943:
Arrives at Hakodate.

24 March 1943:
Departs Hakodate.

27 March 1943:
Arrives at Shimonoseki, Yamaguchi Prefecture.

28 March 1943:
Departs Shimonoseki.

2 April 1943:
Arrives at Dairen.

7 April 1943:
Departs Dairen.

12 April 1943:
Arrives at Fushiki.

14 April 1943:
Departs Fushiki.

15 April 1943:
Arrives at Niigata.

16 April 1943:
Departs Niigata.

18 April 1943:
Arrives at Otaru.

22 April 1943:
Departs Otaru.

23 April 1943:
Arrives at Hakodate.

29 April 1943:
Departs Hakodate.

4 May 1943:
Arrives at Dairen.

9 May 1943:
Departs Dairen.

14 May 1943:
Arrives at Fushiki.

18 May 1943:
Departs Fushiki.

19 May 1943:
Arrives at Nanao, Ishikawa Prefecture.

20 May 1943:
Departs Nanao.

22 May 1943:
Arrives at Otaru.

24 May 1943:
Departs Otaru.

26 May 1943:
Arrives at Ichinose, Toyama Prefecture.

28 May 1943:
Departs Ichinose.

31 May 1943:
Arrives at Otaru.

2 June 1943:
Departs Otaru.

9 June 1943:
Arrives at Chinnampo, Chosen (now North Korea).

14 June 1943:
Departs Chinnampo.

15 June 1943:
Arrives at Dairen.

20 June 1943:
Departs Dairen.

25 June 1943:
Arrives at Nanao.

28 June 1943:
Departs Nanao.

30 June 1943:
Arrives at Otaru.

4 July 1943:
Departs Otaru carrying 1,000-tons of ammunition and steams at eight knots.

6 July 1943:
Arrives at Fushiki.

8 July 1943:
Departs Fushiki.

10 July 1943:
Arrives at Otaru.

14 July 1943:
Departs Otaru.

21 July 1943:
Arrives at Chinnampo.

30 July 1943:
Departs Chinnampo.

31 July 1943:
Arrives at Dairen.

5 August 1943:
Departs Dairen.

10 August 1943:
Arrives at Osaka.

15 August 1943:
Departs Osaka.

16 August 1943:
Arrives at Moji.

22 August 1943:
Departs Moji and arrives at Dairen later that day.

23 August 1943:
Departs Dairen and joins convoy No. 189 that departed Moji that same day, consisting of auxiliary transport KOSEI MARU (2,205 GRT) and four unidentified ships escorted by destroyer ASAGAO.

29 August 1943:
Arrives at Takao, Formosa (now Kaohsiung, Taiwan).

4 September 1943:
Departs Takao and arrives later that day at Mako, Pescadores.

8 September 1943:
Departs Mako (possibly in combined convoys No. 201/204 but unconfirmed).

14 September 1943:
Arrives at Kobe.

17 September 1943:
Departs Kobe.

18 September 1943:
Arrives at Tama. Requistioned that same day by the IJN as a general requisitioned ship (B-AK) (Ippan Choyosen) and attached to the Kure Naval District with Kure as homeport.

10 October 1943:
Departs Tama.

11 October 1943:
Arrives at Tokuyama, Yamaguchi Prefecture.

14 October 1943:
Departs Tokuyama.

15 October 1943:
Arrives at Moji. Departs later in the day for Kure.

16 October 1943:
Arrives at Kure.

22 October 1943:
Departs Kure.

23 October 1943:
Arrives at Saeki, Kyushu.

25 October 1943:
Departs Saeki for Palau, Western Carolines in convoy O-507 also consisting of IJA transports SHOHO, WALES, KISO, TOTAI, YAMATO and KIBI MARUs escorted by kaibokan IKI and auxiliary minesweepers OI, TAMA MARUs, and TAMA MARU No. 7.

E 26 October 1943:
All the auxiliary minesweepers are detached at 30N.

26 October 1943:
Her owners are changed to Mitsui Senpaku K.K. and her registry port to Tokyo.

E 2 November 1943:
Auxiliary subchasers CHa-3, CHa-10 join the convoy near Palau.

4 November 1943:
Off Babelthaup Island, Palau. At 0905, LtCdr (later Rear Admiral) William. B. Sieglaff's (USNA ’31) USS TAUTOG (SS-199) sights a six ship convoy escorted by a "destroyer" and several smaller escorts. At 1045, Sieglaff fires four Mark-18 electric torpedoes, but USS TAUTOG broaches in full view of the Japanese. All the torpedoes miss. The escorts drop five DCs, but USS TAUTOG evades and escapes.

At 1200, USN codebreakers intercept a message from IKI that reads: “At 1045, convoy O [-507] sustained torpedo damage. Position 07-45 N, 134-09 E.”

5 November 1943:
Arrives at Palau.

10 November 1943:
At 1200, departs Palau in convoy No. 507 also consisting of IJA transports CHOSEN, SHOHO and WALES MARUs and four unidentified merchant ships escorted by auxiliary subchasers CHa-3 and CHa-10.

18 November 1943:
At 1600, arrives at Rabaul.

6 December 1943:
At midnight, departs Rabaul for Truk in convoy No. 2063 also consisting of IJA transport HAKUSAN MARU, IJN shared (B/C-AK) TETSUYO MARU and weather ships KAIYO No. 3 and KAIYO No. 4 escorted by subchasers CH-29 and CH-33.

9 December 1943:
At 0945, TETSUYO MARU develops engine trouble and falls behind. CH-33 is detached to escort.

10 December 1943:
The convoy arrives at Truk.

22 December 1943:
At 1000 departs Truk for Yokosuka in convoy No. 4222 also consisting of auxiliary aircraft transport NAGOYA MARU and IJA transport REIYO MARU escorted by kaibokan FUKUE and an unidentified subchaser. Destroyer IKAZUCHI also joins the convoy as an escort.

1 January 1944:
Off Aogashima. At 0258, LtCdr Raymond W. Johnson’s (USNA ’30) HERRING (SS- 233) attacks the convoy. Johnson sets up for a visual attack on the surface. He fires three torpedoes at a large transport and gets a hit in NAGOYA MARU's port quarter causing flooding in holds No's 1 and 2. IKAZUCHI counter-attacks USS HERRING, but her efforts are unsuccessful.

The weather is stormy and heavy seas make damage control difficult. Nevertheless, the crew manages to secure the compartments areas aft of hold No. 2. Later, damage control efforts fail and Captain Kusakawa orders Abandon Ship. IKAZUCHI rescues the survivors.

Coincidentally, that same day and without knowledge of her fate, the IJN rerates NAGOYA MARU as an auxiliary transport attached to the Kure Naval District.

2 January 1944:
NAGOYA MARU becomes increasingly unstable, upends and finally sinks at 32-15N, 138-02E. 110 passengers and one crewman are killed. All or nearly all, probably are killed by the torpedo explosion.

3 January 1944:
Arrives at Yokosuka.

13 January 1944:
Departs Yokosuka for Truk in convoy No. 3113 also consisting of auxiliary transport TATSUTAGAWA MARU escorted by destroyer UMIKAZE and auxiliary minelayer KINJO MARU.

16 January 1944:
Arrives at Chichi-Jima, Ogasawara Gunto (Bonins).

17 January 1944:
Departs Chichi-Jima.

21 January 1944:
Arrives at Saipan, Marianas.

28 January 1944:
Departs Saipan.

1 February 1944:
Arrives at Truk.

12 February 1944:
Departs Truk for Rabaul in convoy No. 1123 also consisting of auxiliary transport (ex- auxiliary gunboat) KOWA MARU escorted by destroyers MINAZUKI and YUZUKI and an unidentified subchaser.

17 February 1944:
Arrives at Rabaul and unloads her cargo.

20 February 1944:
Departs Rabaul for Palau in convoy O-003 also consisting of auxiliary transport (ex- auxiliary gunboat) KOWA MARU and fleet tug NAGAURA evacuating 751st Naval Air Group (Mitsubishi G4M “Betty” bomber) maintenance personnel to Japan, escorted by subchasers CH-37 and CH-38 and auxiliary subchaser CHa-48.

21 February 1944:
N of New Hanover, New Ireland Province. At 1320, the convoy is attacked by 15 North American B-25 "Mitchell" medium bombers of the 5th Air Force's 345th Bomb Group's 500th and 501st Bomb Squadrons that bomb, strafe and sink KOKAI (7 passengers and 19 of the crew KIA) and KOWA MARUs (22 crewmen KIA) and CHa-48 and damage CH-38 heavily at 02-30S, 150-15E. NAGAURA effects repairs then rescues some of the survivors and continues on her voyage north only to be shelled and sunk that night.

30 April 1944:
Removed from the Ippan Choyosen’s list.

Authors' Notes:
* KOKAI MARU has a cruiser stern.

[1] Not to be confused with the auxiliary netlayer (540 GRT, ’39) or the IJA transport (1,272 GRT, ’18).

[2] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without. Thanks go to Gengoro S. Toda of Japan. Thanks go also to Allan Alsleben of Oregon for providing details on “R” and “SR” Operations.

Gilbert Casse, Bob Hackett and Peter Cundall

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