The were a class of escort ships in the service of the Imperial Japanese Navy during World War II. The Japanese called them "Type C" ocean defense ships, and they were the fifth class of Kaibōkan (Kai = sea, ocean, Bo = defense, Kan = ship), a name used to denote a multi-purpose vessel. Background The Type C, like the and es, were dedicated to the anti-aircraft and anti-submarine roles. On 22 April 1943, the Navy General Staff decided a mass production of escort ships, because of the urgent need to protect the convoys which were under constant attack. The plan was to build a basic escort ship of around 800 tons, with a simple design for easy construction. The first designs, for "Type A" and "Type B" , still needed too many man-hours for building, so in June 1943, the Navy General Staff planned for a simplified design. The result was the , and a scaled-down model of the Mikura class, which became the "Type C" and "Type D" escort classes. Design Because of Japan's deteriorating war situation, the Type C was a further simplification of the Ukuru design. They were smaller by 200 tons and the diesel engines that propelled them were also smaller, at versus for the Ukurus. Because of the decrease in engine power, the speed fell from to . The range remained the same, at . The number of guns went from three to two. The number of depth charges aboard was the same, 120, but the number of depth charge throwers was decreased from 18 to 12 and the depth charge chutes were decreased from two to one. Due to the simplifications of the design, a significant saving was made in construction time. The Type C escorts required approximately 20,000 man-hours each, compared to the 35,000 man-hours of the Ukurus and the 57,000 man-hours of the Mikuras. Construction The design work of the Type C ships started in March 1943, the same time as the Ukuru class. They were built concurrently with the Ukuru class and the Type D. The Type C vessels were given odd numbers, while the Type D were given even numbers. The Type C were constructed using prefabricated sections that enabled them to be built in as little as three to four months. The lead ship, No.1 (CD-1) was constructed at Mitsubishi Heavy Industries, laid down on 15 September 1943,