Tabular Record of Movement

© 2008-2018 Bob Hackett and Peter Cundall.

Revision 12

Tamano. Laid down at Mitsui’s shipyard as a 9,205-ton tanker for Mitsui Bussan K.K., Kobe.

E 1936:
Launched and named OTOWASAN MARU.

31 March 1936:
Completed and placed in service with Mitsui Bussan Kaisha. Her maiden voyage is to Los Angeles' San Pedro oil terminal to load and transport oil for Japan's stockpile at Tokuyama Navy oil depot.

28 July 1941:
Arrives at San Pedro to load oil, but two days prior to her arrival, the United States places an embargo on oil exports to Japan to counter Japanese aggression in Asia. OTOWASAN MARU returns to Japan in ballast.

December 1941:
Requisitioned by the IJA with allotted number No. 653. Arrives in SE Asia. Transports crude oil from Palembang, Sumatra to Singapore.

14 December 1941:
Departs Moji.

16 January 1942:
Arrives at Hong Kong.

2 February 1942:
Departs Hong Kong.

10 February 1942:
Arrives at Ujina.

1 March 1942:
At 1230 departs Hesaki for Mako. The ship apparently sails alone.

18 March 1942:
Departs Yokohama.

2 April 1942:
Arrives at Takao.

11 April 1942:
Departs Takao

15 April 1942:
Arrives at Singapore.

25 April 1942:
Departs Singapore in a convoy also consisting of KINUGAWA, KANSA and FUSO MARUs escorted by minelayers KAMOME and TSUBAME.

28 April 1942:
Arrives at Saigon.

17 May 1942:
Arrives at Moji.

19 May 1942:
Departs Moji.

28 May 1942:
At 0900, departs Hesaki in a convoy also consisting of transports RYOYO, NAGARA and YAMAURA MARUs escorted by minelayer NASAMI.

4 June 1942:
Departs Manila.

11 June 1942:
Arrives at Palembang.

15 June 1942:
Departs Palembang.

16 June 1942:
Arrives at Singapore.

17 June 1942:
Departs Singapore.

20 June 1942:
Arrives at Palembang.

24 June 1942:
Departs Palembang.

27 June 1942:
Arrives at Singapore.

30 June 1942:
Departs Singapore.

1 July 1942:
Arrives at Palembang.

6 July 1942:
Departs Palembang.

7 July 1942:
Arrives at Singapore.

10 July 1942:
Departs Singapore.

11 July 1942:
Arrives at Palembang.

13 July 1942:
Departs Palembang.

16 July 1942:
Arrives at Singapore.

21 July 1942:
Departs Singapore.

22 July 1942:
Arrives Palembang.

25 July 1942:
Departs Palembang.

28 July 1942:
Arrives at Singapore.

29 July 1942:
Departs Singapore.

1 August 1942:
Arrives at Palembang.

3 August 1942:
Departs Palembang.

5 August 1942:
Arrives at Singapore.

6 August 1942:
Departs Singapore.

9 August 1942:
Arrives at Palembang.

24 August 1942:
W of Luzon, Philippines. LtCdr Leonard S. Mewhinney's (USNA ’27) USS SAURY (SS-189) torpedoes and severely damages OTOWASAN MARU at 14-15N, 120-19E. She loses power and goes dead in the water.

September 1942:
Undergoes repairs at an unknown location.

26 October 1942:
Departs Manila in convoy 820 also consisting of ASAKASAN MARU and four unidentified merchant ships escorted by destroyer KARUKAYA.

29 October 1942:
Arrives at Mako.

30 October 1942:
Off Mako collides with ASAKASAN MARU. OTOWASAN MARU returns to Mako for repairs.

Early-Mid November 1942:
Departs Mako.

19 November 1942:
Arrives at Hong Kong.

20 December 1942:
Departs from Kowloon, Hong Kong for unknown destination with KASHII, KINKA and ASOSAN MARUs.

4 January 1943:
Departs Hong Kong.

17 January 1943:
Arrives at Kirun (Keelung).

9 February 1943:
Arrives at Osaka.

23 March 1943:
Departs Ujina.

25 March 1943:
Departs Moji in convoy also consisting of cargo ship TEIHOKU MARU (ex French PERSEE) with unknown, if any escort.

1 (or 3) April 1943:
Arrives at Singapore.

3 April 1943:
Arrives at Singapore.

7 April 1943:
At 0800 departs Singapore.

16 April 1943:
At 0415 in 32-45N 134.05E OTOWASAN MARU avoids a torpedo attack while en route to Shimotsu.

29 April 1943:
At 1500 departs Moji in convoy No. 152 also consisting of SEIAN, ATAGO, HAKUBASAN, SHOKO (possibly), BIYO, HAKONE, KENSHIN, JUYO MARUs and KYOEI MARU No. 5 escorted by destroyer KARUKAYA.

3 May 1943:
At 1910 arrives at Mako.

5 May 1943:
Departs Mako in convoy No. 390 also consisting of HAKONE, HAKUBASAN and ATAGO MARUs and three unidentified merchant ships without escort.

11 May 1943:
Arrives at St Jacques.

12 May 1943:
Departs St Jacques in convoy No.579 also consisting of HAKONE and ATAGO MARUs without escort.

15 May 1943:
Arrives at Singapore.

29 May 1943:
Arrives at Yokkaichi.

3 June 1943:
Departs Yokkaichi.

20 June 1943:
At 0900 departs Moji in convoy No. 168 also consisting of two unidentified merchant ships escorted by destroyer KURETAKE.

23 June 1943:
At 1400 arrives at Takao.

30 June 1943:
At 1300 departs Mako and joins convoy No. 304 also consisting of tankers HOKUAN, SEISHIN and NASUSAN MARUs, transports BISAN (ex British MING SANG) and RYUOSAN MARUs and six unidentified merchant ships escorted by auxiliary gunboat HUASHAN (KAZAN) MARU.

6 July 1943:
At 2350 arrives at St Jacques.

9 July 1943:
Departs St Jacques in convoy No.591 also consisting of HOKUAN, ICHIYO, SEISHIN, NASUSAN, RYUYO, RYUOSAN and NICHIAI MARUs escorted by auxiliary minelayer MA-4.

12 July 1943:
At 1230 arrives with tanker SEISHIN MARU at Singapore from St Jacques. It is unclear if the other ships arrived at the same time or earlier or later that day.

17 July 1943:
OTOWASAN MARU departs Singapore in the "L" convoy with transport KIYOKAWA MARU escorted by kaibokan ETOROFU.

23 July 1943:
At about 1240, arrives at Takao, Formosa. At 1200 departs Takao with transport KIYOKAWA MARU in L2 convoy escorted by the destroyer KURETAKE.

26 July 1943:
At 0630 in 31-20N 128-20E OTOWASAN MARU reports a torpedo attack. Submarine chaser KAII and minelayyer TAKASHIMA are summoned and at 1830 KAII makes a contact and starting 1920 and then over the next few minutes drops a total of 14 depth charges. Meanwhile OTOWASAN MARU arrives at Sasebo.

27 July 1943:
Arrives at Tokuyama.

3 August 1943:
Departs Sasebo.

4 August 1943:
Arrives at Kobe.

7 August 1943:
Departs Moji in convoy HI-05 with AKI, HAKUYO and TATEKAWA MARUs and one unidentified merchant ship escorted by destroyer ASAKAZE.

9 August 1943:
Arives at Koniya.

10 August 1943:
Departs Koniya.

13 August 1943:
Arrives at Mako. ASAKAZE is detached and kaibokan MATSUWA takes over escort. OTOWASAN MARU apparently transfers to Takao.

19 August 1943:
Arrives at Singapore.

24 August 1943:
At 1400, the kaibokan MATSUWA departs Singapore escorting convoy HI-06 consisting of KAGU MARU, oilers TATEKAWA and OTOWASAN MARUs and fleet oiler ASHIZURI, together with one unidentified merchant ship.

3 September 1943:
At 0930, arrives at Moji.

10 September 1943:
At 1600, kaibokan MATSUWA departs Moji escorting convoy HI-09 consisting of tankers NICHINAN (5175 gt) and TATEKAWA MARUs, cargo-passenger ship MIIKE MARU, Army landing craft transport AKITSU MARU and two unidentified ships probably tankers MIRI and OTOWASAN MARUs.

21 September 1943:
At Singapore.

28 September 1943:
At 1900, OTOWASAN MARU departs Cap St Jacques for Moji in convoy HI-10 consisting of ASAMA MARU and tankers MIRI and TATEKAWA MARUs and two unidentified merchant ships escorted by kaibokan MATSUWA.

6 October 1943:
Convoy HI-10 is amalgamated with convoy MA-06 (composition unknown).

9 October 1943:
Arrives at Moji.

2 November 1943:
At 1500, OTOWASAN MARU departs Takao in convoy HI-17 consisting of transports ASAMA and KACHIDOKI (ex-PRESIDENT HARRISON) MARUs and fleet oiler TAKASAKI, tankers TATEKAWA, OMUROSAN, OTOWASAN, TARAKAN, ITSUKUSHIMA MARUs, landing craft depot ship AKITSU MARU and transport SAKITO MARU escorted by destroyer FUYO (partway while en route) and kaibokan ETOROFU and MATSUWA.

4 November 1943:
At 1900 arrives at Manila. AKITSU MARU and FUYO detach.

5 November 1943:
At 1430 the convoy departs Manila. FUYO joins as an additional escort.

6 November 1943:
At 1830 ETOROFU is detached from the convoy and begins a submarine hunt.

11 November 1943:
At 1000, arrives at Singapore.

December 1943:
Released from IJA service and returned to commercial service by her owners. Under charter to the IJN, OTOWASAN MARU continues transporting oil from Singapore for the Tokuyama Navy oil depot.

11 December 1943:
Departs Moji in convoy HI-25 also consisting of ZUIHO, JUYO, NISHI, SHOZUI, NICHINAN (5175 gt), KAGU, AMATSU and OMINESAN MARUs escorted by kaibokan TSUSHIMA.

15 December 1943:
JUYO MARU detaches for Kirun. At 1400 arrives in Takao.

16 December 1943:
At 1530 departs Takao. Soon after NISHI MARU (and probably SHOZUI MARU) detaches for Manila.

21 December 1943:
At 1320 arrives at Singapore.

26 December 1943:
At 1000 departs Singapore in HI-26 convoy believed to also consist of AMATSU, OMINESAN MARUs, TAKASAKI and possibly up to three unidentified merchant ships with Kaibokan TSUSHIMA as sole escort. [1]

1 January 1944:
Arrives at Takao. TSUSHIMA Detaches.

3 January 1944:
Departs Takao with convoy increased by addition of SHINSHU, TOZAN, ARIMASAN, OTOWASAN, NOTO, MIIKE and MAYASAN MARUs with light cruiser KASHII as escort. Note that some or all of these may have joined north of Takao.

7 January 1944:
At 1830 arrives at Moji.

20 January 1944:
At 1200, OTOWASAN MARU departs Moji for Singapore in convoy HI-37 also consisting of tankers AMATSU and OMINESAN MARUs, passenger-cargo ships MIIKE and NOTO MARUs and IJA landing craft depot ships KIBITSU and MAYASAN MARUs and an unidentified ship escorted by kaibokan MIYAKE and KANJU.

29 January 1944:
At 1200, arrives at Singapore.

2 February 1944:
At 1300, OTOWASAN MARU departs Singapore in convoy HI-38 also consisting of fleet oiler ASHIZURI and tankers AMATSU, OMINESAN, NICHINAN (5175 gt) and OKIKAWA MARUs, transports KAGU and KACHIDOKI (ex US -PRESIDENT HARRISON) escorted by kaibokan KANJU.

8 February 1944:
At 1700, arrives at Takao.

9 February 1944:
At 1000, departs Takao.

13 February 1944:
Arrives at Moji at 1430.

21 February 1944:
At 0700, OTOWASAN MARU departs Moji in convoy HI-47 also consisting of oilers AMATSU, OMINESAN and KYOKUHO MARUs and NOSHIRO MARU escorted by kaibokan ETOROFU and SADO.

26 February 1944:
At 0850, the convoy arrives at Takao.

27 February 1944:
At midnight, the convoy departs Takao, its number swelled by tankers KUROSHIO, OKIGAWA MARUs and three unidentified merchant ships and kaibokan IKI.

28 February 1944:
Kaibokan SADO is detached from the convoy and returns to Takao.

4 March 1944:
South China Sea, about 300 miles W. of Miri, Borneo. At dawn, LtCdr Charles M. Henderson's (USNA ’34) USS BLUEFISH (SS-222) torpedoes and sinks OMINESAN MARU in shallow water at 05-29N, 108-46E. 46 crewmen are KIA.

5 March 1944:
Arrives at Singapore.

11 March 1944:
At 0730, OTOWASAN MARU departs Singapore for Moji in convoy HI-48 also consisting of tankers OMUROSAN, TATEKAWA, ITSUKUSHIMA, SEIYO, NICHIEI and KUROSHIO MARUs, transport/cargo liners AWA, SANUKI, TEIA (ex-French ARAMIS) and HOKUROKU MARUs and two unidentified ships escorted by kaibokan MIYAKE, SHIMUSHU and IKI.

14 March 1944:
Gulf of Thailand. SANUKI MARU is damaged by a mine or torpedo. The damage causes her to drop out of the convoy on the coast. At 1700, ETOROFU arrives at Van Phong Bay, French Indochina.

15 March 1944:
At 1100, departs Van Phong Bay.

18 March 1944:
At 0114, HOKUROKU MARU is hit by three torpedoes fired by LtCdr Lowell T. Stone's (USNA ’29) USS LAPON (SS-260). One hit causes an induced explosion. HOKUROKU MARU sinks with 6,700-tons of bauxite and 600-tons of crude oil at 19-24N, 116-50E. Eight passengers (out of 256), 25 armed guards and 55 crewmen are KIA. Later that day, KASHII MARU joins the convoy.

19 March 1944:
At 0600, kaibokan SHIMUSHU runs aground, but is refloated later that day. At 1600, the convoy arrives at Takao.

20 March 1944:
At 1300, departs Takao.

25 March 1944:
At 0500, arrives at Moji.

31 March 1944:
At Moji at Mitsubishi Heavy Industries, Ltd. Boat equipment is extended.

1 April 1944:
OTOWASAN MARU departs Moji for Singapore in convoy HI-57 also consisting of tankers ITSUKUSHIMA, OMUROSAN and RYOEI MARUs, IJA landing craft depot ships SHINSHU and MAYASAN MARUs and three unidentified ships (probably tankers SHINCHO and ZUIHO MARUS and one other) escorted by escort carrier KAIYO, kaibokan IKI, SHIMUSHU, CD-8, CD-9 and torpedo boat SAGI.

2 April 1944:
The convoy encounters extremely severe weather and returns to Moji.

3 April 1944:
At 0600, the unchanged convoy departs Moji.

7 April 1944:
At 1450, arrives at Takao.

8 April 1944:
At 1000, departs Takao.

12 April 1944:
At 1930 arrives at Camranh Bay.

13 April 1944:
At 1200, departs Camranh Bay.

16 April 1944:
At 1240, arrives at Singapore.

21 April 1944:
At 0700, OTOWASAN MARU departs Singapore for Moji in convoy HI-58 also consisting of oilers ITSUKUSHIMA, RYOEI, OMUROSAN and probably ZUIHO MARUs, transport KACHIDOKI MARU (ex PRESIDENT HARRISON), IJA landing craft depot ships SHINSHU and likely MAYASAN MARUs escorted by escort carrier KAIYO and kaibokan IKI, SHIMUSHU, CD-8 and CD-9.

24 April 1944:
E of Saigon. USS ROBALO (SS-273) under LtCdr Manning M. Kimmel (son of Admiral H. E. Kimmel, former CINCPACFLT at Pearl Harbor) (USNA ’35) attempts to attack the convoy, but is sighted by a Nakajima B5N2 "Kate” of the 931st NAG detachment from KAIYO. The B5N2 drops one 250-kg depth-charge on the submerged submarine and causes medium damage.

29 April 1944:
Arrives at Takao.

3 May 1944:
HI-58 arrives at Moji.

13 May 1944:
At 0400, OTOWASAN MARU departs Moji for Singapore in convoy HI-63 consisting of cargo liners/transports SANUKI, AWA, TEIA, (ex-French ARAMIS), USSURI and NISSHO MARUS, IJA landing craft depot ships TAMATSU and KIBITSU MARUs, tankers KYOKUHO, SANYO and RYOEI MARUs escorted by kaibokans IKI, MATSUWA, CD-9 and CD-15. SANUKI MARU and the other transports except TAMATSU, KIBITSU and NISSHO MARUs carry troops bound for Burma.

18 May 1944:
At 1800, arrives at Manila. TAMATSU, KIBITSU and NISSHO MARUs are detached.

20 May 1944:
At 2000, the remaining eight ships in HI-63 depart Manila with the same escort.

24 May 1944:
LtCdr (later Cdr) James W. Davis' (USNA ’30) USS RATON (SS-270) attacks the convoy. In a series of attacks, Davis torpedoes and sinks kaibokan IKI A total of 160 sailors, including IKI’s skipper Cdr Nakao Kotaro (57) are KIA; 18 are rescued by kaibokan ETOROFU. Rear Admiral Ijuin Matsuji (43) is also KIA. He is promoted Vice Admiral, posthumously. In the same attack Davis and lightly damages MATSUWA at 01-17N 107-53E. The rest of HI-63 escapes unscathed.

27 May 1944:
At 2000, arrives at Singapore.

29 May 1944:
At 2300 departs Palembang for Singapore at 14 knots.

31 May 1944:
At 1200 arrives Singapore.

6 June 1944:
At 0730, OTOWASAN MARU departs Singapore in convoy HI-64 also consisting of three unidentified merchant ships (probably tankers EIYO, NIYO MARUs and transport TEIA MARU (ex-French ARAMIS) escorted by kaibokan MATSUWA and CD-9.

15 June 1944:
At 0600, arrives at Moji.

13 July 1944:
Arrives at Moji. At 1600, OTOWASAN MARU departs Moji for Singapore in convoy HI-69 also consisting of escort carriers KAIYO and TAIYO, each loaded with aircraft for Luzon, tankers KOEI, HAKKO, OMUROSAN, KUROSHIO, HARIMA, SERIA, TENEI MARUs and transports KIMIKAWA, AKI, ASAMA, SAIGON, KACHIDOKI (ex US-PRESIDENT HARRISON), MANKO MARUs and possibly MANJU MARU escorted by escort carrier SHINYO, light cruiser KASHII and kaibokan CHIBURI, SADO, CD-7 and CD-17. SHINYO's aircraft conduct patrols.

18 July 1944:
Near Takao, Formosa. About 0600, LtCdr (later Cdr) John J. Flachsenhar's (USNA ’35) USS ROCK (SS-274) fires four torpedoes at HARIMA MARU, but misses. Cdr Alan Banister's (USNA ’28) USS SAWFISH (USS 276) fires nine torpedoes at the convoy. HARIMA MARU is hit by a single torpedo, but she remains able to steam. At 1055, LtCdr Roger M. Keithy's (USNA ’35) USS TILEFISH (SS-307) torpedoes and heavily damages CD-17. The convoy continues to Manila without stopping at Takao as originally planned (less MANKO MARU detached the day before and damaged HARIMA MARU and CD-17 that put into Takao).

20 July 1944:
At 2100, arrives at Manila. KAIYO and TAIYO begin unloading aircraft.

24 July 1944:
At 0530, OTOWASAN MARU departs Manila for Singapore in convoy HI-69 that now consists of KIMIKAWA, HAKKO, OMUROSAN, KUROSHIO, SERIA, KACHIDOKI (ex American PRESIDENT HARRISON) and TENEI MARUs escorted by escort carrier SHINYO, light cruiser KASHII and kaibokan SADO, CHIBURI, CD-7, CD-9, CD-13 and CD-19.

31 July 1944:
Arrives at Singapore.

10 August 1944:
At 2100, OTOWASAN MARU departs Singapore for Moji in convoy HI-70 consisting of oilers SERIA, KUROSHIO, OMUROSAN and HAKKO MARUs and MANJU, KINUGASA, ARIMASAN MARUs screened by SHINYO, KASHII, destroyer SHIMOTSUKI and kaibokan CHIBURI, SADO, CD-13 and CD-19.

12 August 1944:
SADO is detached to hunt an enemy submarine.

15 August 1944:
HI-70 arrives at Moji at 1430.

16 August 1944:
Arrives at Yokoshima.

21 August 1944:
Departs Yokoshima. Arrives at Moji later that day.

25 August 1944:
OTOWASAN MARU departs Moji for Singapore in convoy HI-73 also consisting of IJA landing craft depot ship KIBITSU MARU, ex-armed merchant cruiser GOKOKU MARU, ex-seaplane tenders KAGU and SANUKI MARUs, tankers TOHO, OMUROSAN, TAIHO, FUJISAN, HAKKO, AMATO, TOA and KUROSHIO MARUs and fleet storeship IRAKO escorted by escort carrier UNYO, light cruiser KASHII and kaibokan CHIBURI, CD-1,CD-13, CD-19, CD-21 and CD-27.

Later that day, the convoy is joined briefly by transports MIZUHO, ARABIA and KOKURYU MARUs and tanker MANEI MARU.

26 August 1944:
At 0900, MIZUHO, ARABIA and KOKURYU MARUs are ordered away because of excessive smoke. CD-1 also detaches for Sasebo. MANEI MARU remains at Kyushu because of engine problems.

29 August 1944:
Arrives at Takao, Formosa. Departs that same day and arrives at Tsoying (near Takao).

1 September 1944:
Off Saei. The convoy splits. KIBITSU, GOKOKU and KAGU MARUs (and probably IRAKO) head for Manila. The remaining ships head for Singapore.

3 September 1944:
TOA MARU strikes a mine S of Saigon and is lightly damaged, but able to continue.

6 September 1944:
At 0954, arrives at Seletar, Singapore.

11 September 1944:
OTOWASAN MARU departs Seletar for Moji in convoy HI-74 also consisting of tankers AZUSA, HARIMA, OMUROSAN and HAKKO MARUs escorted by escort carrier UNYO, light cruiser KASHII (F) and kaibokan CHIBURI, CD-13, CD-19, CD-21 and CD-27.

16 September 1944:
At 2231, OMUROSAN MARU is hit by a torpedo fired by Cdr (later Rear Admiral) Charles E. Loughlin's (USNA ’33) USS QUEENFISH (SS-393). At 2334, oiler AZUSA MARU is hit by two of a salvo of six bow torpedoes fired by Cdr (later Rear Admiral) Eugene B. Fluckey's (USNA ’35) USS BARB (SS-220). AZUSA MARU blows up and sinks with six gunners and 36 out of 42 crewmen. UNYO is hit by other torpedoes in Fluckey's salvo and settles aft.

17 September 1944:
At 0755, UNYO sinks by the stern at 19-10N, 116-35E. More than 900 crewmen and passengers are lost as are 48 aircraft.

18 September 1944:
Arrives at Takao.

23 September 1944:
At 1700, arrives at Moji.

1 October 1944:
At 0800, OTOWASAN MARU departs Moji for Singapore in convoy HI-77 also consisting oilers OMUROSAN, ARITA, ITSUKUSHIMA, AKANE, TAIHO and KAIHO MARUs, transports MANJU (ex-SANTOS) and KINUGASA and ORYOKU MARUs, German submarine supply ship QUITO (KITO-GO) and an unidentified vessel escorted by kaibokan CHIBURI and CD-19, CD-21 and CD-27.

5 October 1944:
Arrives at Takao. Before departing later the same day, HI-77’s escort is bolstered by inclusion of kaibokan ETOROFU and SHONAN.

6 October 1944:
250 miles W of Manila. After patrolling the Luzon Strait, a wolfpack consisting of LtCdr (later Captain) Arnold H. Holtz’s (USNA ’31) USS BAYA (SS-318), LtCdr Henry D. Sturr’s (USNA ’33) USS BECUNA (SS-319) and LtCdr Francis W. Scanland, Jr’s (USNA ’34) USS HAWKBILL (SS-366) heads through the South China Sea towards Fremantle, Australia.

About 1400, LtCdr (later Captain) James B. Grady's (USNA ’33) USS WHALE (SS-239) torpedoes and sinks oiler AKANE MARU. 63 crewmen and 747 troops are KIA. At 1757, Cdr (later Rear Admiral) Charles W. Wilkins' (USNA ’24) USS SEAHORSE (SS-304) torpedoes and sinks CD-21. Her entire complement of 170 men is lost with an unknown number of survivors from AKANE MARU rescued earlier.

7 October 1944:
At about 2200, KINUGASA MARU is hit by three more torpedoes. At 2224, USS HAWKBILL, running on the surface, fires four torpedoes and gets three hits followed by an ammo explosion. LtCdr Holtz’s USS BAYA also torpedoes and sinks KINUGASA MARU. 10 passengers and 33 crewmen are KIA.

12 October 1944:
At 1500, the remainder of HI-77 arrives at Singapore.

20 October 1944:
At 1800, OTOWASAN MARU departs Singapore in convoy HI-78 consisting of tankers TOHO and ARITA MARUs escorted by kaibokan ETOROFU and SHONAN.

22 October 1944:
Kaibokan TSUSHIMA joins the escort.

27 October 1944:
The convoy is attacked by USAAF aircraft at 20-42N, 114-36E, but they are beaten off without loss.

3 November 1944:
Arrives at Iwakuni.

6 November 1944:
Departs Iwakuni and arrives at Ujina later that same day.

9 November 1944:
Departs Ujina.

10 November 1944:
Arrives at Moji.

13 November 1944:
Departs Moji and arrives at Imari Wan. OTOWASAN MARU departs Imari Bay for Singapore in convoy HI-81 consisting of SHINSHU, KIBITSU, AKITSU, ARITA, HASHIDATE, KIYOKAWA, MAYASAN, MIRII and TOA MARUs escorted by kaibokan ETOROFU (F), TSUSHIMA, DAITO, KUME, SHONAN, CD-9 and CD-61 and escort destroyer KASHI. The convoy stops overnight at Goto Island.

15 November 1944:
Departs Goto Island. Escort carrier SHINYO takes up position at the rear of the center of three columns of vessels. At 1156, LtCdr (later Rear Admiral) Charles E. Loughlin's (USNA ’33) USS QUEENFISH (SS-393) torpedoes and sinks AKITSU MARU. 67 crewmen, 140 gunners, 2,093 of 2500 men of the IJA's 64th Infantry Regiment are KIA. Her load of IJA's 20th Sea Raiding Battalion 104 “Maru-ni” explosive motor boats (EMB) aboard are also lost. SHINYO's planes attempt to locate and destroy the submarine, but fail to find her.

16 November 1944:
Off Korea. The convoy anchors near Strange Island and shelters there.

17 November 1944:
At 0800, convoy HI-81 departs for the Shushan Islands near Shanghai. At 1815, USS PICUDA (SS-382) torpedoed and sinks MAYASAN MARU with the loss of 56 crewmen, 194 gunners and 3187 of 4,387 men and 204 horses of IJA’s 23rd Division are KIA. All maru-ni explosive motor boats (EMBs) of IJA's 24th Sea Raiding Battalion are also lost. At 2309, LtCdr (later Cdr) Gordon W. Underwood’s (USNA ’32) USS SPADEFISH (SS-411) torpedoes and sinks escort carrier SHINYO. Over 700 sailors are KIA and fewer than 200 are rescued. Escort destroyer KASHI counterattacks the submarine with uncertain results.

18 November 1944:
At 0315, kaibokan TSUSHIMA attacks a submarine with fifteen depth-charges. At 1600, the convoy arrives at Ssu Chiao Shan anchorage.

21 November 1944:
The convoy departs for Mako, Pescadores.

23 November 1944:
Formosa Strait. The convoy anchors in the Nanjih Channel. Kaibokan CD-61 joins escort.

24 November 1944:
At 0730, departs the Nanjih area.

25 November 1944:
CD-61 is detached from the convoy.

26 November 1944:
Arrives at Mako. CD-9 joins the escort.

27 November 1944:
At 1600, convoy HI-81 departs Mako for Singapore. It now consists of OTOWASAN, ARITA, HASHIDATE and TOA MARUs escorted by kaibokan ETOROFU (F), KUME, CD-9 and CD-61 and escort destroyer KASHI.

4 December 1944:
Arrives at Singapore.

12 December 1944:
At 1600, OTOWASAN MARU departs Singapore in convoy HI-82 also consisting of tankers OMUROSAN, ARITA, PALEMBANG and HASHIDATE MARUs escorted by kaibokan ETOROFU, SHONAN, KUME, CD-9 and CD-19. OTOWASAN MARU carries a cargo of gasoline.

17 December 1944:
Arrives at Camranh Bay.

19 December 1944:
Departs Camranh Bay.

22 December 1944:
25 miles E of Quang Ngai, Indo-China. At 0550, LtCdr (later Captain) George W. Grider's (USNA ’36) USS FLASHER (SS-249) torpedoes OTOWASAN, OMUROSAN and ARITA MARUs. All three tankers burst into flames. At 0550, after being hit amidships by two torpedoes, OTOWASAN MARU sinks at 15-07N, 109-05E. Captain Murotsu Masaichi, 56 troops, one passenger and 62 seamen are KIA.

OMUROSAN and ARITA MARUs also sink. Two of the crew of OMUROSAN MARU and 57 of ARITA MARU crew are KIA.

Authors’ Note:
[1] ICHIYO MARU may possibly have been in this convoy but was more likely in HI-24.

[2] HI-31 was the first carrier escorted convoy.

Photo credit goes to the Dan Wheeler collection via Ron Wolford and Gilbert Casse. General thanks to Mr. Gilbert Casse and Gengoro Toda of Japan.

- Bob Hackett and Peter Cundall.

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