(Sister KASUGA MARU, prewar)
Tabular Record of Movement
© 2013-2016 Gilbert Casse, Bob Hackett and Peter Cundall
Innoshima. Laid down by Osaka Iron Works K.K shipyard for Naigai Kisen K.K. as a 3,991-ton cargo ship.
24 February 1940:
Launched and named SHINKOKU MARU. 
12 October 1940:
Completed and registered in Kobe. Her Net Registered Tonnage (NRT) is 2,344-tons. 
Her NRT is changed to 2,332-tons. 
18 February 1942:
Requisitioned by the IJN.
20 February 1942:
Provisionally rated as a General Requisitioned ship (Ippan Choyosen).
21 February 1942:
Provisionally attached to the Sasebo Naval District.
25 February 1942:
Registered in the IJN as an auxiliary transport attached to the Maizuru Naval District with Maizuru as home port under
instruction No. 354.
1 March 1942:
Tactically assigned to Vice Admiral (later Admiral) Tsukahara Nishizo’s (36) 11th Air Fleet, Supply Unit as an auxiliary transport (Otsu) category. 
Embarks 50 800-kgs and 150 250-kgs bombs.
9 March 1942:
Departs Takao, Formosa (now Kaohsiung, Taiwan).
16 March 1942:
At midnight arrives at Singapore, Malaya.
1 April 1942:
4 April 1942:
Arrives at Sabang, Sumatra.
10 April 1942:
Assigned to supply Air Bases.
11 April 1942:
14 April 1942:
Arrives at Singapore.
15 April 1942:
18 April 1942:
Arrives at Bangkok, Siam (now Thailand).
21 April 1942:
24 April 1942:
Arrives at Saigon, Indochina (now Ho Chi Minh City, Vietnam).
25 April 1942:
29 April 1942:
Arrives at Takao.
1 May 1942:
4 May 1942:
Arrives at Furue, Hyuga-Nada. Departs later that same day.
5 May 1942:
Arrives at Sasebo.
9 May 1942:
10 May 1942:
Arrives at Furue. Departs later in the day.
16 May 1942:
Arrives at Tinian, Marianas.
17 May 1942:
Departs Tinian and arrives at Saipan, Marianas later that day.
20 May 1942:
26 May 1942:
Arrives at Taroa, Marshalls.
28 May 1942:
29 May 1942:
Arrives at Wotje, Marshalls.
31 May 1942:
12 June 1942:
Scheduled to be fitted with auxiliary transport (Otsu) category’s standard armament equipment under Navy’s secret instruction No. 7246.
22 June 1942:
Auxiliary transport (Otsu) category’s standard armament equipment fittings begins.
11 July 1942:
Departs Otaru, Hokkaido.
24 July 1942:
Arrives at Roi-Namur, Marshalls.
28 July 1942:
Departs Roi-Namur and arrives at Kwajalein, Marshalls later in the day.
11 August 1942:
12 August 1942:
Arrives at Wotje.
13 August 1942:
14 August 1942:
Arrives at Taroa.
25 August 1942:
Departs Taroa and arrives at Mili, Marshalls later that same day.
30 August 1942:
Departs Mili and arrives at Emiedj, Marshalls later that same day.
1 September 1942:
Departs Emidj and arrives at Jaluit later that day.
3 September 1942:
Departs Jaluit, Marshalls and arrives at Kwajalein later in the day.
7 September 1942:
8 September 1942:
Arrives at Roi-Namur and departs later that same day for Japan.
13 September 1942:
Arrives at Yokosuka.
16 September 1942:
Scheduled to be fitted with depth-charges (DCs) equipment under Navy’s secret instruction No. 11672.
22 September 1942:
1 October 1942:
Arrives at Yokkaichi, Mie Prefecture.
4 October 1942:
5 October 1942:
About 100 nautical miles NE of Aogashima Island, Izu Shoto. At dawn, LtCdr (later Rear Admiral) Roy S. Benson’s (USNA ’29) USS TRIGGER (SS-237) sights smoke on the horizon and heads for it. As the target approaches, the submarine identifies it as a small ship. USS TRIGGER then surfaces and mans her machine guns, scoring some hits. As the target nears, however, the submarine learns that the Japanese ship is larger than initially thought. Enemy shells soon begin exploding close to USS TRIGGER, and SHINKOKU MARU turns and accelerate in an attempt to ram the submarine. USS TRIGGER barely avoids a collision as she submerges for an attack; Benson launches two torpedoes and hears one hit. The submarine then surfaces and gave chase, only to have the target again open fire. Benson misses with three more torpedoes and then discontinues the pursuit. SHINKOKU MARU is only slightly damaged and resumes her course.
16 October 1942:
Arrives at Taroa.
17 October 1942:
Departs Taroa and arrives at Kwajalein later in the day.
18 October 1942:
Departs Kwajalein and arrives at Jaluit later that day.
22 October 1942:
23 October 1942:
Arrives at Emiedj.
1 November 1942:
Tactically assigned to the Southeast Area, Supply Unit.
15 February 1943:
At 0500, departs Emiedj escorted by auxiliary subchaser KYO MARU No. 7.
16 February 1943:
Arrives at Kwajalein for bunkers.
18 February 1943:
At 0500, departs Kwajalein for Saipan (ETA Saipan 24 February).
E 20-21 February 1943:
SHINKOKU MARU is reported missing after 18 February. Most sources credit LtCdr Phillip H. Ross’s (USNA ’27) USS HALIBUT (SS-232) for the sinking, probably 280 nautical miles NW of Eniwetok Atoll, at 15-09N, 159-30E. Another source states the ship was en-route to Kwajalein from Ponape when sunk. Casualties also are contradictory. Most sources state the ship sank with all hands but some Japanese source reports only 11 crewmen KIA.
1 April 1943:
Removed from the Navy’s list under instruction No. 587.
 Not to be confused with auxiliary oiler (10,020 GRT ’40)
or IJA transport No. 1150 (2,746 GRT, ’43)
 NRT is a ship's cargo volume capacity expressed in "register tons",
one of which equals to a volume of 100 cubic feet (2.83 m3). It is calculated by
reducing non-revenue-earning spaces i.e. spaces not available for carrying
cargo, for example engine rooms, fuel tanks and crew quarters, from the ship's
gross register tonnage (GRT). Net register tonnage (NRT) is not a measure of the
weight of the ship or its cargo, and should not be confused with terms such as
deadweight tonnage or displacement.
 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.
Gilbert Casse, Bob Hackett and Peter Cundall
IJN Transports Page