The was a class of submarine in the Imperial Japanese Navy (IJN), which served during the Second World War. The Type-A submarines were built to take a role of the command ships for submarine squadrons. For this reason they had equipment for a headquarters, better radio facilities and a floatplane. Class variants The Type-A submarines were divided into four classes: . The 5094th vessel class boats were not built and remained only a design. Type-A (I-9 class) Project number S35Ja. Their design was based on the Junsen III (I-7 class). Three boats were built in 1938-42 under the Maru 3 Programme (Boat # 35 - 36) and Maru 4 Programme (Boat # 138). Boats in class Type-A Mod.1 (I-12 class) Project number S35B. Five boats were planned under the Maru Tsui Programme (Boat # 620 - 621) and the Kai-Maru 5 Programme (Boat # 5091 - 5093). They were equipped with less powerful diesel engines which shortened the time needed to build them. Only one boat, , was completed to the original design. The I-13 and the later boats were converted to a new submarine class (I-13 class), because the number of I-400 class boats was reduced. Boats in class Type-A Mod.2 (I-13 class) Project number S35C. Four boats were planned under the Maru Tsui Programme (Boat # 621) and the Kai-Maru 5 Programme (Boat # 5091 - 5093). However, four boats were converted to new submarine class (I-13 class), because a number of submarines of the I-400 class were cancelled. They had a large hangar and were equipped with bulges to be able to operate 2 × special Aichi M6A1 Seiran attack bombers. The headquarters institutions were removed. Boats in class V21 Type Project number S48. Three boats were planned under the Kai-Maru 5 Programme. However, all boats were cancelled in late 1943, because the IJN turned its attention to the construction of in 1945. Boats in class Characteristics Footnotes Bibliography , History of Pacific War Vol.17 "I-Gō Submarines", Gakken (Japan), January 1998, Rekishi Gunzō, History of Pacific War Vol.63 "Documents of IJN submarines and USN submarines", Gakken (Japan), January 2008, Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, Model Art Extra No.537, Drawings of Imperial Japanese Naval Vessels Part-3, Model Art Co. Ltd. (Japan), May 1999, Book code 08734-5 The Maru Special, Japanese Naval Vessels No.13,