The was a class of three oilers of the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 (IJN), serving during the 1920s and the World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

.

Construction

The Ondo class were initially planned in 1920 as the six of the Kamoi class oiler

Japanese seaplane tender Kamoi

The was a oiler/seaplane tender/flying boat tender of the Imperial Japanese Navy, serving during the 1920s and the World War II. She was initially planned in 1920 as one of six of the oilers under the Eight-eight fleet final plan.-Service:...

s under the Eight-eight fleet

Eight-eight fleet

The was a Japanese naval strategy formulated for the development of the Imperial Japanese Navy in the first quarter of the 20th century, which laid down that the Japanese navy should include eight first-class battleships and eight armoured cruisers or battlecruisers.-History and development:The...

 final plan. However, the Kamoi class oilers were built only the Kamoi, because the Washington Naval Treaty

Washington Naval Treaty

The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...

 was concluded. Other five vessels were re-planned to the Modified Notoro class oiler. And one vessel became the icebreaker Ōtomari

Japanese icebreaker Ōtomari

The was a icebraker of the Imperial Japanese Navy serving during the 1920s through World War II, the only ship of her class. She was an only icebreaker as warship in the IJN.-Background:...

, other one vessel become the food supply ship Mamiya

Japanese food ship Mamiya

The was a food supply ship of the Imperial Japanese Navy which was in service from the 1920s to the Second World War.-Construction:The Mamiya was originally meant to be an oil transporter but was instead out-fitted to be a food supply ship...

. Therefore, three vessels was built as Modified Notoro class (Ondo class) oiler.

Service in peace time

They devoted themselves to importing crude oil from North America and Southeast Asia. The crude oil which the Ondo class and the Notoro class

Notoro class oiler

The was a class of seven oilers of the Imperial Japanese Navy , serving during the 1920s and the World War II. They were also called the , after the Notoro and the Shiretoko were converted to other ship types.-Construction:...

 carried to Japan was 388 sorties; 3,000,000 tons, until 1941.

Service in Pacific War

They were not able to accompany to fleet, because they were low speed. They were engaged in a supplying duties at the naval bases.

Ships in class

Ship	Builder	Laid down	Launched	Completed	Fate
	Kawasaki-Kōbe Shipyard	15-03-1922	21-10-1922	12-03-1923	Sunk by air raid at Manila Bay Manila Bay Manila Bay is a natural harbor which serves the Port of Manila , in the Philippines.The bay is considered to be one of the best natural harbors in Southeast Asia and one of the finest in the world...  13-11-1944.
	Kure Naval Arsenal	14-03-1922	04-12-1922	18-05-1924	Scuttled off Singapore Singapore Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the... , 1946. Decommissioned on 03-05-1947.
	Yokosuka Naval Arsenal	11-04-1922	30-01-1923	30-10-1924	Heavy damaged by air raid at Rabaul Rabaul Rabaul is a township in East New Britain province, Papua New Guinea. The town was the provincial capital and most important settlement in the province until it was destroyed in 1994 by falling ash of a volcanic eruption. During the eruption, ash was sent thousands of metres into the air and the... , 14-01-1944 and grounded. Damaged once again 02-03-1944. Scuttled 15-03-1944.
2 vessels					Re-planned to the icebreaker Japanese icebreaker Ōtomari The was a icebraker of the Imperial Japanese Navy serving during the 1920s through World War II, the only ship of her class. She was an only icebreaker as warship in the IJN.-Background:...  and food supply ship Japanese food ship Mamiya The was a food supply ship of the Imperial Japanese Navy which was in service from the 1920s to the Second World War.-Construction:The Mamiya was originally meant to be an oil transporter but was instead out-fitted to be a food supply ship... .