Ha-3-class submarine

The was an early class of submarines of the Imperial Japanese Navy.
Background.
Along with placing orders with Vickers at Barrow-in-Furness in the UK for two British C-class submarines, which were commissioned into the Imperial Japanese Navy as the , the Japanese government ordered another three vessels, which were received as knock-down kits. These kits were assembled at the Kure Naval Arsenal.
Design.
Physically almost identical to the "Ha-1" class, the three vessels assembled in Japan incorporated a number of improvements, including extended bow for improved seaworthiness, improved rudder for surface handling, and an increase in the size of the bridge and conning tower.