(OTORI MARU hull on the stocks. No photo or plan of the completed vessel has been located)
IJN OTORI MARU:
Tabular Record of Movement
© 2015-2018 Gilbert Casse and Peter Cundall
Osaka. Laid down by Namura Zosensho K.K. shipyard for Kita Nihon Kisen K.K. as a 2,105-tons cargo ship.
Launched and named OTORI MARU. <1>
17 March 1943:
Completed and registered at Tokyo.
29 June 1943:
Rated as 2nd Navy ship.
30 June 1943:
1 July 1943:
Arrives at Moji.
5 July 1943:
11 July 1943:
Arrives at Maoka, Karafuto (now Kholmsk, Sakhalin).
18 July 1943:
24 July 1943:
Arrives at Same, Aomori Prefecture.
27 July 1943:
2 August 1943:
Arrives at Funakawa, Oga Peninsula, Akita Prefecture.
5 August 1943:
14 August 1943:
Arrives back at Funakawa.
17 August 1943:
Departs again from Funakawa.
29 August 1943:
Arrives at Otaru, Hokkaido.
31 August 1943:
2 September 1943:
Arrives at Esutoru, Karafuto (now Uglegorsk, Sakhalin).
5 September 1943:
9 September 1943:
Arrives at Hakodate, Hokkaido.
12 September 1943:
13 September 1943:
Arrives at Kamaishi, Iwate Prefecture.
20 September 1943:
28 September 1943:
Arrives N of Ozawa, Fukushima Prefecture.
30 September 1943:
Departs Ozawa waters.
5 October 1943:
At 2247 in 39-00N 139-24E reports a torpedo attack.
6 October 1943:
Arrives at Niigata, Honshu.
8 October 1943:
Departs Niigata, Honshu.
10 October 1943:
Arrives at Maizuru. Requisitioned that same day by the IJN as a general requisitioned ship.
12 October 1943:
Starts conversion to military duty at Maizuru Naval Yard.
16 October 1943:
24 October 1943:
25 October 1943:
Arrives at Moji to prepare for departure to Singapore 
9 November 1943:
At 0700, departs Takao and at 1700 arrives at Mako. Steams at 8.5 knots.
12 November 1943:
Departs Takao in convoy No. 337 also consisting of IJA transport FUKUYO MARU, IJN requisitioned cargo ship (B-AK) DAIHO MARU, civilian emergency tanker (C-AO)TAKETSU (BUTSU) MARU and two unidentified merchant ships escorted by auxiliary gunboat HUASHAN (KAZAN) MARU.
16 November 1943:
Her owners are changed to Osaka Shosen K.K. (OSK).
17 November 1943:
Arrives at St Jacques, French Indochina (now Vung Tau, Vietnam).
20 November 1943:
Departs St Jacques for Singapore.
24 December 1943:
At 0200, departs Surabaya, Java in an unnumbered convoy also consisting of IJA transport AMAGI MARU escorted by minelayer ITSUKUSHIMA.
29 December 1943:
At 1340, arrives at Ambon, Moluccas. Departs later.
1 January 1944:
Registered in the Navy’s list as an auxiliary transport (Otsu) category attached to the Maizuru Naval District with Maizuru as home port under instruction No. 16. Assigned that same day to Vice Admiral (later Admiral) Takasu Shiro’s (35) Southwest Area Fleet. 
6 January 1944:
At 0900 departs Ambon escorted by auxiliary minesweeper Wa-3.
8 January 1944:
At 0730 arrives at Kokas.
10 January 1944:
At 1600 departs Kokas escorted by auxiliary minesweeper Wa-3.
12 January 1944:
At 1715, arrives at Ambon.
13 January 1944:
Confirmed as an auxiliary transport (Otsu) category under Navy’s secret instruction No. 143. The conversion is completed that same day.
17 January 1944:
At 1200 departs Ambon in a convoy also consisting of TAITO and BIZEN MARUs escorted by auxiliary submarine chaser SHONAN MARU No. 17.
19 January 1944:
At 1800 arrives at Kendari.
20 January 1944:
Undergoes specific maintenance related to auxiliary transport (Otsu) category.
27 January 1944:
Arrives at Surabaya, Java.
20 May 1944:
About five nautical miles off Semangka Bay, southern tip of Sumatra. About 1800, LtCdr Robert I. Olsen’s (USNA ’33) USS ANGLER (SS-240) makes a submerged attack against a merchant ship. He fires four Mark XIV TYPE 3A torpedoes and scores one hit on OTORI MARU’s stern. The transport sinks at 05-40N, 105-27E with the loss of four of her crew.
10 November 1944:
Removed from the Navy’s list under instruction No. 1258.
Authors' Notes :
 Not to be confused with IJA transport OTORI (ex-Panamanian BOYACA) MARU (2,559 GRT, ’20).
 Convoy No. 110 that left Mutsure on 30 Oct and arrived at Takao on 4 Nov ‘43 probably contained OTORI MARU. A small passenger ship, OSHIMA MARU is shown in this convoy and appears out of place. Although the primary source undoubtedly states OSHIMA MARU there is a strong suspicion that this is an error for OTORI MARU.
 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 and Peter Cundall.
IJN Transports Page