The was a group of medium-sized coastal submarines built for the Imperial Japanese Navy (IJN) during World War II. The IJN official designation for this class was or . They are also known as Type KS submarine. The type name was shortened to .The read as "Shō" and the read as "Sen-Shō", but the read as "Ko-gata" and the read as "Sen-Shō-gata" in Japanese.

Design and description In 1940, the IJN designed a point-defence coastal submarine because they wanted to save their larger submarines for fleet battles. The Ro-100 class was derived from the preceding Kaichū type. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had a double hull and a diving depth of .Carpenter & Dorr, p. 123

For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Ro-100s had a range of at ; submerged, they had a range of at .Chesneau, p. 204

The boats were armed with four internal bow torpedo tubes and carried a total of eight torpedoes. They were also armed with two single mounts for Type 96 anti-aircraft guns or a single L/40 AA gun.Bagnasco, p. 193

Boats 18 boats were built in 1941-1944 under the Maru Rin Programme (Boat #210-218) and the Maru Kyū Programme (Boat #400-408). Boat # Name Builder Laid down Launched Completed Results Fate 210 . The same shall apply hereinafter. Kure Naval Arsenal 1941-06-30 1941-06-12 1942-08-23 Sunk by naval mine off Bougainville Island 1943-11-25. 211 Kawasaki-Kōbe Shipyard 1941-09-30 1942-04-17 1942-10-31 Sunk by and PBY southeast of San Cristobal 1943-09-15. 212 Kawasaki-Kōbe Shipyard 1941-09-30 1942-04-17 1942-11-17 Disappeared south of Rabi after 1943-05-09.Although her loss is credited to PT-150 and PT-152 off Lae, New Guinea on 13/14 May 1943, the submarine was later confirmed as I-6, which survived the encounter. 213 Kure Naval Arsenal 1941-06-30 1941-12-06 1942-10-21 Sank 1943-06-23Sank 1943-06-23 Disappeared in the Solomon Islands after 1943-07-28, possibly sunk by a mine or a PT boat. 214 Kawasaki-Kōbe Shipyard 1941-11-19 1942-07-11 1943-02-25 Sunk by north of the Admiralty Islands 1944-05-23. 215 Kawasaki-Kōbe Shipyard 1941-11-19 1942-07-11 1943-03-05 Sunk by north of the Admiralty Islands 1944-05-31. 216 Kure Naval Arsenal 1941-12-17 1942-05-30 1942-12-26 Sank 1943-07-11 Sunk by north of the Admiralty Islands 1944-05-22. 217 Kure Naval Arsenal 1941-12-17 1942-05-30 1942-12-26 Sunk by east of Kolombangara 1943-07-21. 218 Kawasaki-Kōbe Shipyard 1942-04-20 1942-10-26 1943-04-20 Sank 1943-10-03 Sunk by north of the Admiralty Islands 1944-05-26. 400 Kawasaki-Kōbe Shipyard 1942-04-20 1942-10-26 1943-04-29 Sunk by south of Okinawa Island 1945-04-25. 401 Kawasaki-Kōbe Shipyard 1942-08-20 1943-01-26 1943-07-06 Sunk by , and in the Bay of Bengal 1944-02-12. 402 Kawasaki-Kōbe Shipyard 1942-08-20 1943-01-26 1943-07-10 Sank RMS Peshawar 1943-12-23 Sunk by north of the Admiralty Islands 1944-06-10. 403 Kawasaki-Senshū Shipyard 1942-06-20 1943-03-25 1943-09-14 Sunk by in the Luzon Strait 1945-02-11. 404 Kawasaki-Senshū Shipyard 1942-07-11 1943-04-24 1943-10-12 Sunk by in the Luzon Strait 1945-02-12. 405 Kawasaki-Senshū Shipyard 1942-10-12 1943-06-19 1943-11-20 Sunk by and east of Saipan 1944-06-17. 406 Kawasaki-Senshū Shipyard 1942-10-12 1943-06-19 1943-11-30 Sunk by , and west of Mindoro 1945-02-01. Holmes contradicts the identification,Holmes, W. J., 1966, Undersea Victory: The Influence of Submarine Operations on the War in the Pacific, pg. 428-429 indicating that Ro-115 acknowledged orders to proceed to Manila two days after the supposed date of its sinking, and was more likely to have been sunk by on 1945-02-10.Which sub was it? http://www.ussbatfish.com/whichsub.html 407 Kawasaki-Senshū Shipyard 1943-01-16 1943-09-13 1944-01-21 Sunk by north of the Admiralty Islands 1944-05-24. 408 Kawasaki-Senshū Shipyard 1943-01-16 1943-09-13 1944-01-31 Sunk by USN patrol bomber southeast of Saipan 1944-05-24.

Footnotes

Bibliography

, History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-43 The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36