Japanese seaplane tender Notoro. was an oiler of the Imperial Japanese Navy commissioned in 1920, which was rebuilt in 1924 into a seaplane tender and in 1941 back into an oiler. She participated in the First Shanghai Incident in 1932 and the Second Sino-Japanese War since 1937. In the fall of 1941, she was rebuilt back into an oiler. On 9 January and 20 September 1943, she was damaged by US Navy submarines but returned to service after repairs. On 29 June 1944, she was hit by two torpedoes launched by submarine . During repairs in Singapore Notoro was again damaged on 5 November 1944, this time by B-29 bombers. No further repairs were made until the end of the war and she was probably scrapped in 1947.

Designation of airplanes operating from Notoro 
Aircraft operating from Notoro were marked on the tail with a code, according to the following scheme: [code Notoro] - [tactical number]. The identification code Notoro changed during the service. After her conversion to a seaplane tender, the code was formed by three katakana written characters ノ ト ロ (no to ro). In October 1937, the code was changed to 13. In October 1941 the code was  Z1  and in November of that year - just before the conversion back to an oiler - the code was changed to  N2 .

Onboard aircraft complement
The number of aircraft up to 1941 was as follows. (The number of aircraft is regular + reserve aircraft) 
28 June 1927: 4+4 Yokosuka E1Y reconnaissance aircraft
8 May 1929: 6+2 Yokosuka E1Y reconnaissance aircraft (1 Yokosuka K1Y trainer fixed on the outside in 1929)
25 May 1932: Yokosuka E1Y3 4+2, Yokosuka E5Y reconnaissance seaplane 2+1.
1 November 1932: Yokosuka E1Y3, Yokosuka E5Y 3+1.
30 January 1933: Yokosuka E1Y3, Yokosuka/Kawanishi E5Y/K 6+2.
15 October 1933: Nakajima E4N2 4+1.
1 May 1934: E4N2 6+2 (some are E1Y3 reconnaissance aircraft).

After repairs in 1937, she is reported to carry 4 Kawanishi E7K and 4 Nakajima E8N reconnaissance seaplanes.

In July 1941 her aircraft complement was moved to Fujikawa Maru, and Notoro aircraft group was disbanded.

Notoro service as a seaplane tender (1924 to 1941)

Notoro was the second commissioned ship of the Notoro-class oilers. She was completed as an oiler with a carrying capacity of 8,000 tons, but relatively shortly after her commission, it was decided to convert her into a seaplane tender. The refit was completed at the Sasebo Naval Arsenal on 1 June 1924. As a seaplane tender Notoro could carry up to eight (six operational and two dismantled backup machines) three-seater Type 14 reconnaissance seaplanes (later designated Yokosuka E1Y1). Notoro had no catapult: seaplanes took off from the water surface, where they were unloaded by ship cranes. After the refit, Notoro could continue to act as an oiler.

On 1 December 1925 Notoro was assigned to the Combined Fleet.

An explosion occurred on Notoro on 5 September 1931 when she was moored at the Port of Yokohama, causing 10 deaths, destroying aviation fuel tanks and damaging several E1Y1 seaplanes.

 
From the beginning of 1932, Notoro participated in operations against China (but initially independent from the Combined Fleet). On 28 January Notoro arrived in Shanghai from the Ryojun naval base. The tense situation in Shanghai that day escalated into the first Shanghai incident. On the night of January 28 and 29, seaplanes from Notoro dropped flares to scare off the Chinese opposition. The next day, Notoro, moored on the  Yangtze River, sent several of her E1Y3 seaplanes against targets in Shanghai. Despite the foggy weather, seaplanes attacked targets in Zhabei (), artillery positions outside the city and an armored train at the Shanghai North railway station (). However, the raids also claimed civilian casualties, which caused outrage in China.

On 11 May 1932, Notoro was reassigned to the Combined Fleet, and on 25 May the aircraft complement was changed to include three-seater seaplanes E5K / E5Y.

On 2 October 1937 Notoro received the second half of the E8N2 seaplanes from the 23rd Reconnaissance Group, which were delivered to the shores of South China by the submarine tender Taigei.

On 24 February 1938 Notoro was located on the shores of South China Sea. That morning, Notoro sent out five of its E8N2s, to which were added eight E8N2s from Kinugasa Maru to attack Nanxiong (in the northern Guangdong province). Some E8N2 carried bombs and some flew armed only with their machine guns as an escort. Above the target, the E8N faced twelve Gladiator Mk. I of the 28th and 29th zhongdui (; squadron) of the 5th  dàduì (; air group/wing) of the Chinese Air Force. E8N proved to be a difficult prey. During the battle, several E8Ns were damaged, with two (including one from Notoro) crashing on the way back with the loss of their crews. Another damaged E8N2 (tailcode 13-1) from Notoro, which was hit a total of 138 times, returned with a dead observer on board and was written off after an emergency landing. Another E8N also returned with a dead crew member. Notoro lost a total of five dead aircrew members and two E8Ns. The Chinese lost two Gladiators (Nos. 2902 and 2808) and their pilots during the battle.

On 24 July 1938, Notoro together with Kamikawa Maru provided air support for Kure's 5th "Kaigun tokubetsu rikusentai" (), a Special Naval Landing Forces unit, which landed on the banks of the Yangtze River. Between 12 and 25 October, Notoro together with the seaplane carrier Kamoi and the aircraft carriers Kaga, Sōryū and Ryūjō supported the Japanese offensive in the Guangdong Province, during which Guangzhou fell to the Japanese on 21 October.

Notoro service as a tanker (1941 to 1945)
 
The planned invasion of the Southwest Pacific created the need for the Imperial Japanese Navy to transport oil from future occupied territories in the Dutch East Indies to Japan. Notoro was therefore rebuilt back into a tanker in November and December 1941.

During the Pacific War Notoro sailed between Japan and the Japanese bases in the Southwest Pacific and the Indian Ocean. On 9 January 1943 Notoro became the target of a submarine attack by  in the Makassar Strait, she was hit by at least two of the three fired torpedoes. However, the tanker was able to continue to Balikpapan at Borneo, where the most necessary repairs were made. She then proceeded for further repairs to Singapore where she arrived on 31 January 1943.

On 26 May 1943 she sailed in the convoy No. 4526 from Truk. The convoy was headed for Yokosuka but was attacked on 3 June by the submarine . All seven torpedoes fired by the submarine missed and the convoy arrived in Yokosuka on 5 June.

On 20 September 1943 Notoro sailed from Truk as part of the convoy No. 4920 to Japan. After departing the harbor, at 23:00 hours at  west of Truk , Notoro was hit by a torpedo from the submarine  and had to return to Truk. The repairs lasted until 24 January 1944.

On the evening of 25 June 1944, Notoro sailed as part of the convoy MISHI-03 from Miri, Borneo, to Singapore. On the evening of 28 June the convoy was spotted by the submarine , which attacked after midnight on 29 June. Of the three torpedoes fired at Notoro, two or all three struck the tanker and Notoro stopped dead in the water. On the afternoon of 30 June Notoro was towed to Singapore, but repairs were slow. In addition, the ship was severely damaged in the King George VI Graving Dock of the Sembawang shipyard on 5 November 1944 during an air raid by 53 B-29 bombers of the USAAF and subsequently the ship was decommissioned. Until the end of the war, it was used as a floating fuel tank. In 1947 Notoro was either scrapped or sunk as a breakwater near Pulau Brani by the British.

On 3 May 1947 Notoro was struck from the list of ships of the Japanese Navy.

Footnotes

References

Sources
 
 
 

1920 ships
Notoro-class oilers
Seaplane tenders of the Imperial Japanese Navy
Ships built by Kawasaki Heavy Industries