The was one of the naval expansion plans of the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 (IJN).

Background

In November 1941, the IJN required many additional submarines for the Pacific War, as a pressing matter. To meet this need, the IJN negotiated with the Ministry of Finance

Ministry of Finance (Japan)

The ' is one of cabinet-level ministries of the Japanese government. The ministry was once named Ōkura-shō . The Ministry is headed by the Minister of Finance , who is a member of the Cabinet and is typically chosen from members of the Diet by the Prime Minister.The Ministry's origin was back in...

 and received approval for 32 submarines and one target ship. Later, they were concluded by 78th, 79th and 81st Imperial Diet

Imperial Diet

Imperial Diet means the highest representative assembly in an empire, notably:* the historic institution of the Imperial Diet , either the estates in the Holy Roman Empire...

.

Table of vessels

Category	Class	Vessel number(s)	Completed	Converted	Cancelled
Cruiser submarine Type-A	I-12	#620, #621	I-12 Japanese submarine I-12 The submarine I-12 was a Japanese A2 type submarine. She was built at the Kawasaki's shipyard in Kobe.-Wartime service:The I-12 sailed from the Inland Sea on 4 October 1944 to disrupt American shipping between the west coast and the Hawaiian Islands.... (#620)	#621 was converted to the I-13 class
	I-13		I-13 Japanese submarine I-13 Japanese submarine I-13 was an AM type submarine. The submarine was built at the Kawasaki shipyard in Kobe.... (#621)
Cruiser submarine Type-B	I-54	#627, #629, #631, #633 - 636	I-54 (#627), I-56 (#629), I-58 Japanese submarine I-58 I-58 was a Japanese B3 type cruiser submarine that served in the final year of World War II. Modified to carry Kaiten manned torpedoes, she damaged two enemy destroyers with them, but her most significant success was the , sunk with conventional torpedoes on 30 July 1945... (#631)		#633 - 636
Cruiser submarine Type-C	I-52	#625, #626, #628, #630, #632	I-52 (#625), I-53 (#626), I-55 (#628)		#630, #632
Medium sized submarine	Ro-35	#640 - 654	Ro-56 (#645)		#640 - 644, #646 - 654
Tanker submarine	I-351 Japanese submarine I-351 The Japanese submarine was a tanker/transport submarine of the Imperial Japanese Navy , serving during 1945. The IJN called this type of submarine .-Construction:Project number S47...	#655 - 657	I-351 (#655)		#657
Target ship	Hakachi Japanese target ship Hakachi The was a bomb target ship of the Imperial Japanese Navy serving during the Second World War, the only ship of her class.-Background:Project number J32. In before the pacific war, the IJN wanted to raise the training efficiency of bomber for the outbreak of war...	#660	Hakachi (#660)