Ondo-class oiler

The Ondo class oiler (隠戸型給油艦) was a class of three oilers of the Imperial Japanese Navy (IJN), serving during the 1920s and World War II.

Construction
The Ondo-class were initially planned in 1920 as the six of the Kamoi class oilers under the Eight-eight fleet final plan. However, of the Kamoi class oilers, only the Kamoi was completed, due to the conclusion and signing of the Washington Naval Treaty. The other five vessels were then re-planned to the Modified Notoro class oiler.

Out of the five ships, one became the icebreaker Ōtomari, other become the food supply ship Mamiya. Therefore, only three ships were 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 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.