Ha-201-class submarine

The Ha-201 class submarine (波二百一型潜水艦) were a class of small submarines designed for the Imperial Japanese Navy (IJN). They were first deployed in 1945, but never saw combat. The Ha-201's were designed from the outset to have high under water speed and were based on the earlier Submarine No.71 prototype. The official designation of the submarine was Submarine High speed-Small type (潜高小型).

Construction
At the end of 1944 the IJN decided it needed large numbers of high-speed coastal submarines in preparation for the allied Operation Downfall. 79 boats were planned under the Maru Sen Programme (Boat #4911-4989), however only 9 boats were completed by the end of war. The Japanese navy planned to prefabricate large sections of the boats, then finish the boats in the slipway, ambitious considering the allied bombing campaign that was disrupting Japanese production. These submarines displayed many of the same advanced ideas implemented on the German Type XXI and Type XXIII submarines.