The were a class of ships in the service 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...

 during 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...

.

The Japanese called these ships Kaibōkan, "ocean defence ships", (Kai = sea, ocean, Bō = defence, Kan = ship), to denote a multi-purpose vessel.
The fourteen ships of the Etorofu class were a major part of Japan's escorts from the middle of World War II. They were denoted "Improved Type A" ships, and were the second class of Kaibōkan. The Etorofus, unlike the , received more emphasis on submarine warfare.

The Etorofu class was initially armed with thirty-six depth charges and would later rise to 60 depth charges with an 8 cm trench mortar and six depth charge throwers. The rise of aircraft also saw the number of AA machine guns increase to 15. They would receive Type 22 and Type 13 radars and Type 93 sonar in 1943-1944.

The ships of the class were the Etorofu (択捉), Hirado (平戸), Tsushima

Japanese escort ship Tsushima

Tsushima was an escort ship of the Imperial Japanese Navy during World War II....

 (対馬), Fukue (福江), Matsuwa

Japanese escort ship Matsuwa

was an escort ship of the Imperial Japanese Navy during World War II.On 2 August 1944 Matsuwa was torpedoed and sunk by USS Harder in Hidai Bay....

 (松輪), Mutsure (六連), Sado (佐渡), Oki (隠岐), Manju (満珠), Kanju (干珠), Iki (壱岐), Amakusa

Japanese escort ship Amakusa

Amakusa was an escort ship of the Imperial Japanese Navy during World War II....

(天草), Wakamiya (若宮), and Kasado (笠戸).

Eight of the fourteen ships, Hirado, Iki, Amakusa, Kanju, Wakamiya, Sado, Mutsure, and Matsuwa were sunk during the war.