Ro-100-class submarine

The Ro-100-class submarine (呂百型潜水艦) was a medium size submarine of the Imperial Japanese Navy (IJN), serving during World War II. The IJN official designation for this class was Small Type (小型) or Submarine-Small Type (潜小型).

Construction
Project number S45. In 1940, the IJN planned a point-defence submarine, because the IJN wanted to use their large-sized submarine for naval battles. 18 boats were built in 1941-1944 under the Maru Rin Programme (Boat #210-218) and the Maru Kyū Programme (Boat #400-408).