IRO.
Built as a Navy tanker by Osaka Iron Works, Sakurajima for the Imperial Japanese Navy.
02 September 1921 keel laid down.
05 August 1922 launched under the name IRO, named after a rocky cape on the southern point of the half island Izu. She is one of the Shiretoko class navy oilers.
Tonnage 6.500 gross tons, displacement 15.450 tons. Dim.
Powered by 2 VTE engines, 5.850 shp. twin shafts. Speed 14 knots.
Armament 2 – 5.5 inch, 2 – 80mm AA guns.
Cargo capacity 8.000 tons oil.
30 October 1922 completed. Registered in the Kuru Naval District.
31 October 1941 assigned to the Fourth Japanese Fleet.
08 December 1941 she sailed from Kwajalein to support the invasion on Wake Island, returning 13 December.
30 April support the “Operation MO” the invasions of Tulage and Port Moresby. IRO remains at Shortlands as a Station Tanker.
After the Battle of the Coral Sea, “Operation MO” is cancelled and the IRO with the attack fleet returns to Rabaul.
30 May 1942 she sails from Rabaul for a drydocking in Kure where she arrived on 30 May.
Then she returned to Rabaul where she arrived on 11 July.
Used in the shuttle oil service between Rabaul and Truk.
27 February 1943 she departs from Jaluit, the same day in a position West of Jaluit at about 09.00 she is torpedoed by USS PLUNGER. Hit by one torpedo and the IRO became unnavigable, towed back to Jaluit by KATORI MARU and as escort SHONAN MARU No 11 where she arrived on 04 March.
23 May after some repairs were made, departed from Jaluit under tow of the cargo liner OKITSU MARU.
10 June 1943 still under tow torpedoed by USS TINOSA in position 31 14N 132 44E, she sustained some flooding but continues under tow.
12 June she arrived at Kuru after towed for 4.600 miles.
After repair and drydocking sailed 08 December 1943 from Saeki for Palau in convoy -803, she was on 10 December detached from the convoy and arrived 18 December at Palau, then she head for Balikpapan to load 8000 tons of crude-oil.
Thereafter used in the transport of crude-oil and refined oil from Indonesia.
15 March 1944 she sails in convoy from Balikpapan for Palau.
22 March 1944 the convoy is attacked by USS TUNNY, one of the torpedoes hit the IRO in the bow, forward of the bulkheads.
23 March 1944 the IRO arrived at Palau.
30 March 1944 in Operation “Desecrate One” American planes attack the anchorage of Palau.
31 March 1944, TF 58’s planes find and attack the IRO anchored in a sheltered lagoon close to Koror, Peleliu.
She received a direct bomb hit in the engine room and is set on fire. Of the soldiers on board 250 survive; Captain Kitamura is killed during the action.
IRO burns for days on 17 April 1944 she sinks in 130 feet of water.