The was a type of the 1st class submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 in 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...

 serving during the Second World War. The was different from the I-361 class, however since the I-373 was a development form of the I-361 class, this article describes both of them.
The IJN called them as follows:

• I-361-class : , , or .
• I-372 : .
• I-373-class : .

Construction

After the Battle of Midway

Battle of Midway

The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

 the IJN immediately planned a transport submarine. The type was based on the U 155 Deutschland

German submarine Deutschland

Deutschland was a blockade-breaking German merchant submarine used during World War I. It was developed with private funds and operated by the North German Lloyd Line...

. Her duties were transportation of troops (110 men, 10 tons freight and 2 landing crafts) in the areas where the enemy had air superiority. Later the demands for her were changed in sequence. The final demands were 65 tons in the hull and 25 tons on the upper deck (freight only). In the beginning the IJN did not intend to equip these boats with torpedo

Torpedo

The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

s. Later, after strong demands from the front commanders, it was decided to equip them with torpedoes for self-defense. The I-372 class was designed as a tanker submarine based on the I-361 class. They were not allowed to be loaded with torpedoes.

Service

In 1944, their missions were transport from mainland Japan to remote islands. They had little success and suffered big damages. Of the 13 submarines, only 4 survived war.

Kaiten missions

In 1945, 7 submarines were converted to be Kaiten

Kaiten

The Kaiten were manned torpedos and suicide craft, they were used by the Imperial Japanese Navy in the final stages of World War II.-History:...

mother ships and assigned to the suicide attack operations for the . They removed all guns and piled up five Kaitens on upper deck.

• I-361
  • Assigned to the on 24 May 1945, no success.
• I-363
  • Assigned to the Todoroki group on 28 May 1945, sank (or damaged) one motor ship on 15 June 1945.
  • Assigned to the on 8 August 1945, no success.
• I-366
  • Assigned to the Tamon group on 1 August 1945, no success.
• I-367
  • Assigned to the on 5 May 1945, damaged USS Gilligan
    USS Gilligan (DE-508)
    USS Gilligan was a John C. Butler-class destroyer escort acquired by the U.S. Navy during World War II. The primary purpose of the destroyer escort was to escort and protect ships in convoy, in addition to other tasks as assigned, such as patrol or radar picket...
    
     on 27 May 1945.
  • Assigned to the Tamon group on 19 July 1945, no success.
• I-368
  • Assigned to the on 20 February 1945, no success.
• I-370
  • Assigned to the Chihaya group on 20 February 1945, no success.
• I-372
  • No sorties.

I-361 class

Boat #	Name	Builder	Laid down	Launched	Completed	Fate
5461	I-361	Kure Naval Arsenal	16 February 1943	30 October 1943	25 May 1944	Converted to a Kaiten mother ship on 7 February 1945. Sunk by aircraft from USS Anzio USS Anzio (CVE-57) USS Anzio , was an Casablanca class escort carrier of the United States Navy.Originally classified as auxiliary aircraft carrier ACV-57, was laid down on 12 December 1942 by the Kaiser Shipbuilding Co., Vancouver, Washington, under a Maritime Commission contract ; named Alikula Bay on 22 January...  at east of Okinawa Island Okinawa Island Okinawa Island is the largest of the Okinawa Islands and the Ryukyu Islands of Japan, and is home to Naha, the capital of Okinawa Prefecture. The island has an area of...  22°22′N 134°09′E on 30 May 1945.
5462	I-362	Mitsubishi, Kōbe Shipyard	17 March 1943	29 November 1943	23 May 1944	Sunk by USS Fleming USS Fleming (DE-32) USS Fleming was an built for the United States Navy during World War II. While performing convoy and escort duty in the Pacific Ocean she was also able to sink one Japanese submarine and to shoot down several kamikaze planes that intended to crash onto her...  at Caroline Islands Caroline Islands The Caroline Islands are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically they are divided between the Federated States of Micronesia in the eastern part of the group, and Palau at the extreme western end...  12°08′N 130°28′E on 18 January 1945.
5463	I-363	Kure Naval Arsenal	1 May 1943	12 December 1943	8 July 1944	Converted to a Kaiten mother ship on 30 March 1945. Sunk by naval mine off Miyazaki Miyazaki, Miyazaki is the capital city of Miyazaki Prefecture on the island of Kyūshū in Japan. Located on the coast and perforated by several rivers, Miyazaki City enjoys scenic views of both ocean and nearby, verdant mountains...  on 29 October 1945. Salvaged and scrapped on 26 January 1966.
5464	I-364	Mitsubishi, Kōbe Shipyard	26 July 1943	15 February 1944	14 June 1944	Sunk by USS Sea Devil USS Sea Devil (SS-400) USS Sea Devil , a Balao-class submarine, was the first ship of the United States Navy to be named for the sea devil , the largest of all rays, noted for power and endurance.-Construction and commissioning:...  at Bōsō Peninsula Boso Peninsula thumb|Locationthumb|Landsat image with high-resolution data from Space Shuttle is a peninsula in Chiba prefecture on Honshū, the largest island of Japan. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean....  34°30′N 145°23′E on 15 September 1944.
5465	I-365	Yokosuka Naval Arsenal	15 May 1943	17 December 1943	1 August1944	Sunk by USS Scabbardfish USS Scabbardfish (SS-397) USS Scabbardfish , a Balao-class submarine, was the only ship of the United States Navy to be named for the scabbarddfish, a long, compressed, silver-colored fish found on European coasts and around New Zealand....  at Tōkyō Bay Tokyo Bay is a bay in the southern Kantō region of Japan. Its old name was .-Geography:Tokyo Bay is surrounded by the Bōsō Peninsula to the east and the Miura Peninsula to the west. In a narrow sense, Tokyo Bay is the area north of the straight line formed by the on the Miura Peninsula on one end and on...  34°44′N 141°01′E on 28 November 1944.
5466	I-366	Mitsubishi, Kōbe Shipyard	26 August 1943	29 March 1944	3 August 1944	Converted to a Kaiten mother ship on 3 March 1945. Decommissioned on 30 November 1945. Sunk as target off Gotō Islands Goto Islands The are Japanese islands in the East China Sea, off the western coast of Kyūshū. The islands are a part of Nagasaki Prefecture.- Geography :There are 140 islands in total, including five main islands:,,,, and....  on 1 April 1946.
5467	I-367	Mitsubishi, Kōbe Shipyard	22 October 1943	28 April 1944	15 August 1944	Converted to a Kaiten mother ship on 1 January 1945. Decommissioned on 30 November 1945. Sunk as target off Gotō Islands Goto Islands The are Japanese islands in the East China Sea, off the western coast of Kyūshū. The islands are a part of Nagasaki Prefecture.- Geography :There are 140 islands in total, including five main islands:,,,, and....  on 1 April 1946.
5468	I-368	Yokosuka Naval Arsenal	15 July 1943	29 January 1944	25 August 1944	Converted to a Kaiten mother ship in early 1945. Sunk by aircraft from USS Anzio at west of Iwo Jima Iwo Jima Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...  24°07′N 140°19′E on 27 February 1945.
5469	I-369	Yokosuka Naval Arsenal	1 September 1943	9 March 1944	9 October 1944	Converted to a tanker submarine in June 1945; decommissioned on 15 September 1945. Surrendered to United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...  at Yokosuka Yokosuka, Kanagawa is a city located in Kanagawa, Japan. As of 2010, the city had an estimated population of 419,067 and a population density of 4,160 people per km². It covered an area of 100.62 km²... , later scrapped.
5470	I-370	Mitsubishi, Kōbe Shipyard	4 December 1943	26 May 1944	4 September 1944	Converted to a Kaiten mother ship in early 1945. Sunk by USS Finnegan USS Finnegan (DE-307) USS Finnegan was an constructed for the United States Navy during World War II. She was sent off into the Pacific Ocean to protect convoys and other ships from Japanese submarines and fighter aircraft...  at south of Iwo Jima Iwo Jima Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...  22°45′N 141°27′E on 26 February 1945.
5471	I-371	Mitsubishi, Kōbe Shipyard	22 March 1944	21 July 1944	2 October 1944	Sunk by USS Lagarto USS Lagarto (SS-371) USS Lagarto , a Balao-class submarine, was the only ship of the United States Navy to be named for the lagarto, a lizard fish.Her keel was laid down on 12 January 1944 by the Manitowoc Shipbuilding Company of Manitowoc, Wisconsin...  at Bungo Channel Bungo Channel The is a strait separating the Japanese islands of Kyūshū and Shikoku. It connects the Pacific Ocean and Seto Inland Sea. The narrowest part of this channel is the Hōyo Strait....  32°40′N 132°33′E on 24 February 1945.

I-372 class

Project number S51B. She was going to become a lead ship of the Modified Type D submarines (I-373 class), at first. However, the IJN wanted a submarine as soon as possible. She was built to tanker submarine by a revised I-361 drawings.

Boat #	Name	Builder	Laid down	Launched	Completed	Fate
2961	I-372	Yokosuka Naval Arsenal	10 February 1944	22 June 1944	8 November 1944	Converted to a Kaiten mother ship on 16 February 1945. Sunk by USN carrier aircraft from Task Force 38 at Yokosuka Yokosuka, Kanagawa is a city located in Kanagawa, Japan. As of 2010, the city had an estimated population of 419,067 and a population density of 4,160 people per km². It covered an area of 100.62 km²...  on 18 July 1945.

I-373 class

Project number S51C. Improved model of the I-361 class. Furthermore, the IJN was planned reinforced model of the I-373 class, also. However all of they were cancelled.

Boat #	Name	Builder	Laid down	Launched	Completed	Fate
2962	I-373	Yokosuka Naval Arsenal	15 August 1944	30 November 1944	14 April 1945	Converted to a tanker submarine in June 1945; sunk by USS Spikefish USS Spikefish (SS-404) USS Spikefish , a Balao-class submarine, was a ship of the United States Navy. Spikefish was the first United States submarine to record 10,000 dives...  at East China Sea East China Sea The East China Sea is a marginal sea east of China. It is a part of the Pacific Ocean and covers an area of 1,249,000 km² or 750,000 square miles.-Geography:... 29°02′N 123°53′E on 13 August 1945.
2963	I-374	Yokosuka Naval Arsenal	24 October 1944			Construction stopped on 17 April 1945 (40 % complete), later scrapped.
2964	I-375					Cancelled on 17 April 1945.
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