From the end of World War II to the 50s, when the Japan Maritime Self-Defense Force was founded, it received U.S. assistance from the United States to build 14 destroyers of the 4th class, and had an overwhelming advantage in Northeast Asia. 
On September 2, 1945, Japan surrendered, and subsequently the Japanese army was disarmed. Article 9 of the Constitution of Japan, promulgated in 1946, stipulates that the renunciation of war, the denial of war forces and belligerent rights. In terms of the navy, the Navy Ministry was dissolved and reorganized into the Second Department of Demobilization, which took over some of the responsibilities of demobilization and dredging of sea routes. In 1946, the Ministry of Communications established a garrison responsible for maritime security. In June 1950, the Korean War broke out. In order to deal with mines, Japan formed a mine-sweeping force to participate in the Korean War, and the personnel were ** employees. In this way, Japan was demilitarized while participating in combat missions, and Japan took the opportunity to expand. On October 19, 1951, the United States announced that it would lease 18 patrol ships (PFs) and 50 landing support craft (LSLs) to Japan. In order to receive and operate these **, Japan secretly decided to set up a special division within the Maritime Guard, separate from other patrol vessels, and decided to complete it before the entry into force of the San Francisco Peace Treaty. 
On April 26, 1952, the Coast Guard was transferred to the Japan Coast Guard. On June 9, 1954, the Japanese Diet passed the Law on the Establishment of the Defense Agency and the Self-Defense Forces Law, upgrading the Security Agency to the Defense Agency, and reorganizing the Army, Navy and Air Force in the name of the Self-Defense Forces. On July 1, 1954, the Maritime Guard was officially organized as the Maritime Self-Defense Force, with an establishment of 7,828 personnel, mainly composed of former Japanese Navy soldiers, and the old Japanese Navy flag and military song were used. After that, the name "ship" was resurrected, and in 1953 the shipbuilding plan "guard ship" was renamed "guard ship", the "supply work ship" was renamed "minelayer", the large minesweeper was renamed "minesweeper", and the small minesweeper was renamed "medium minesweeper". In the early days of the Second Maritime Self-Defense Force, the main force was 18 Nan-class garrison boats, which were leased from the United States in 1953 and were originally Tacoma-class escort patrol ships during World War II. In terms of large ships, like Italy, Type 1 destroyers were the remnants of World War II aided by the United States. On October 19, 1954, the United States officially handed over two old Greaves-class destroyers to Japan, namely Ellyson (DD454) and Macomb (DD458), named DD181 Chaofeng and DD182 Flag Wind. 
This pre-war design of the destroyer was typical of the type of ship with a short bow. In order to reduce the offensive character, when the United States delivered to Japan, it dismantled one MK30 127 mm naval gun and torpedo tubes in front of the bridge, although the firepower was castrated and could not be compared with the Japanese special destroyers in World War II, it was still the most powerful ship in the sea and Northeast Asia at that time. The sides of the hull are painted with large katakana names, just like the old Japanese Navy. In 1959, Japan leased two Fletcher-class fleet destroyers, named DD183 Ariake and DD184 Yudu. This classic destroyer of the World War II fleet has completely backward in its ability to search and attack submarines. After the two ships entered Japan, they underwent radical anti-submarine transformation, and built a new Japanese-style flying scissor bow, equipped with Alpha anti-submarine rocket depth bombs and hull sonar. 
There are not many bright spots in the armament of the four ships of the 2nd class, and Japan has obtained American-style radar, fire control and other electronic equipment, which is Japan's shortcoming. In addition, Japan has acquired navigation replenishment technology and experienced good habitability, which will be reflected in Japan's domestic ships one after another. Third, at the policy level, in 1956, the Sea of Japan adopted the "First Defense Force Rearmament Plan", planning to build a series of "guard ships", including two types of aircraft carrier programs. Limited to the basic requirements of the "Peace Constitution" to focus on defense, as well as the people's unforgettable memories of the atomic bomb and the Li Mei fire attack, Japan's peace forces vetoed all the non-divisions of the sea, and finally planned to build 16 small and medium-sized ships**. From 1954 to 1960, under the name of "garrison ships", Japan successively started the construction of a total of 14 destroyers of the four classes: Chunfeng, Lingbo, Murayu (first generation), and Akizuki (second generation). 
The Chunfeng class is a mixed race and adopts the American flat-deck boat type. The hull is made in Japan, and the armament and electronic equipment are all from the United States, and the comprehensive combat performance is much better than that of the old Japanese Navy destroyers. The first ship was commissioned in 1956, and a total of two ships were built, with the port number DD, and successively served as the flagship of the Self-Defense Forces. 
Ayana-class anti-submarine destroyer
The Murayu-class (first-generation) air defense destroyer destroyer cannot integrate all armaments due to size limitations, and the classification is gradually refined. Under the influence of the United States, sea self-destroyers are divided into anti-submarine type (DDK), air defense type (DDA), and command type (DDC). Among them, the anti-submarine type is the Ayanami class, the first ship was commissioned in 1958, and 7 ships were built, mainly 3 double-barreled 76mm main guns (front 2 rear mm torpedoes, anti-submarine based on hedgehog shells, with a maximum speed of 32 knots; The air defense type is the Murayu class (first generation), the first ship was commissioned in 1959, and 3 ships were built, with the port number DDA107-109, and the main ** is 3 MK39 single-mounted 127 guns (1 in the front and 2 in the rear).
Akizuki-class destroyer.
Akizuki-class destroyer (this is refitted)In 1960, the Akizuki-class destroyer, built with funds from the United States, entered service. This type of ship is further enlarged than the previous two types of ships, and in order to protect the flagship personnel, the superstructure has formed a unique large box-shaped structure. Equipped with the most advanced RUR-4 Alpha anti-submarine rocket depth bomb at that time, it had good multi-purpose performance and was positioned as a command destroyer (DDC). A total of 2 ships were built in the Akizuki class, with the port number DDC, and successively served as the flagship of the Self-Defense Force and the Escort Force. Compared with the cramped spring breeze level, the autumn moon class can provide better accommodation conditions. Fourth, these destroyers, which seemed to have limited technological progress, were extremely rare at the time: all were built from scratch as capital ships. The new ship began to use a new long-bow model, all powered by steam turbines. At the same time, three countries designed and built new ships in batches: France, Japan and Italy. France was a strong power, and the latter two were separated from the east and west of the Eurasian continental island to contain the Soviet Union. At the strategic level, Japan has multiple considerations: First, the layout of the shipbuilding industry. Japan adopted a decentralized strategy to build ships, comprehensively laid out the shipbuilding industry, and integrated it into the post-war reconstruction process. In the Lingbo class, for example, Mitsubishi Shipbuilding Nagasaki Shipyard built 2 ships, Kawasaki Heavy Industries Kobe Plant built 1 ship, Mitsui Shipbuilding Ono Shipyard built 2 ships, Ishikawajima Heavy Industries built 1 ship, and Iino Heavy Industries Maizuru Shipyard built 1 ship. The second is to form two development paths. On the one hand, as a manifestation of political vassalage, receiving American aid. On the other hand, the integration of Japan and the United States, that is, the Japanese hull plus American-style armaments and electronic equipment, has been practiced since the Chunfeng class. The third is to gradually carry out innovation. In terms of ship type, the design of the long bow tower is adopted to increase the internal space and adapt to the electronic development of shipboard equipment. At that time, the only ships with the long bow type were the British Whitby-class frigates and the Canadian Saint Laurent-class destroyers. The strength of the connection between the front and rear broken steps is the weak point of the long bow ship type, and the strength problem was solved by designing a continuous deck with a gentle slope (about 13 degrees). After its use, this sloping deck became known as the "Dutch Slope", and although it was inaccessible and unpopular, it eventually became a Japanese tradition.
On the psychological level, Japan, bound by shame, has adopted two contradictory paths to convince itself. One is to adopt a completely American design. The Spring Breeze class abandoned almost all the traditions of the Japanese destroyer, the product of absolute submission under political vassalage. In contrast to the self-conscious Italian Navy, Japan knelt quickly and thoroughly. The second is to use the trick of covering your ears and stealing the bell. In the name of Type A and Type B garrison ships, Japan built Chun-class destroyers and Akebo-class frigates respectively, which was not only the inheritance of the Japanese Navy and Japan's tradition of deception, but also the first step for the Navy to confuse destroyers as frigates. As the saying goes, three years old is big, and seven years old is old. In the 50s, with these ships as the main body, the Navy organized a self-defense ship group, a local team, and a base team, and the subordinate units were the sea sweeping team and the aviation team, and completed the reorganization of the organization. At the cultural level, a large number of the old Japanese navy inherited the traditions of the old Japanese navy, played word games with foreign countries, and became the eastern vassal of the United States to contain the island of Eurasia.