These ships were numerous and played a very active role in Pacific naval combat but have never been the subject of a book in English until now. During the Second World War, the Imperial Japanese Navy used the term kaibokan to refer to several classes of ships. The kaibokans slotted below Imperial Japanese destroyers, comparable to the British Royal Navy's frigates and corvettes or American destroyer escorts. A total of 171 vessels were completed in the kaibokan family, making it one of if not the most produced warship design by the Imperial Japanese Navy during the war. These ships were numerous and played a very active role in Pacific naval combat. This is the illustrated history of the type, including a historical synopsis, full technical description, and more than 100 photographs and diagrams. Naval historians Lars Ahlberg and Hans Lengerer have established themselves as experts on and specialists in the warships of the Imperial Japanese Navy during WWII. Their work is differentiated by being primarily driven by the utilization of Japanese-language primary source material.