The series focuses on both a technologically-advanced Imperial Japanese Navy and a radically-different World War II that were brought about by Admiral Isoroku Yamamoto's revival by unexplained circumstances.

It also spawned a 1997 OVA side story, Kyokujitsu no Kantai (旭日の艦隊, literally "Fleet of the Rising Sun"), one manga sequel, and two turn-based strategy games for the PC-FX and the Super Famicom.

Otaka, who has also been transported back in time, agrees to work with Yamamoto to change history and ensure that the Japanese Empire emerges victorious against the United States in the Second World War.

Yamamoto uses his advanced knowledge of the future and the now-superior technology of the Imperial Japanese Navy to ensure that the strategy and the outcome of the attack are considerably different from in our timeline: Following its successful invasion, Japan uses Hawaii as its main North Pacific base.

In subsequent battles in the Tasman Sea and the Torres Strait, the Imperial Navy further cripples American naval power and advances across the Pacific Ocean to strike at the West Coast of the United States.

A Japanese submarine-carrier flotilla destroys the Panama Canal's Gatun locks, which significantly hinders American efforts to transfer ships from the Atlantic Fleet to the Pacific theater.

The US suffers more crushing setbacks, including a second Panama Canal attack and a long-range surgical airstrike on the Manhattan Project's Los Alamos facilities.

Although the Japanese are initially allied with Nazi Germany, the German dictator, Heinrich von Hitler, becomes concerned about their string of victories and the rapid growth of Japan's technological and military power, which was boosted partly by the expertise of Albert Einstein.

Hitler declares war on Japan, whose first thrust against Germany comes in the form of a precision attack by three intercontinental flying-boat bombers on the Germans' atomic weapons research facility.

Japan fights off the Kriegsmarine's attacks in the South Atlantic while the allied British-Japanese forces in England muster enough combat power to push the Germans back and to liberate London.

In the 1997 side story Shin Kyokujitsu no Kantai (新旭日の艦隊: "The New Fleet of the Rising Sun"), Japan builds up on its success in the earlier series by expanding its blue-water capabilities to reach the Atlantic Ocean.

The story further details the presence of the Japan's Atlantic fleet revealed in the latter half of Konpeki no Kantai and expound on events that had been given only a passing mention in the series.

[15][16] The Japanese Navy later attacks German naval facilities in Kiel, the government quarter in Berlin, and a French-based battery of Heracles railway guns threatening London, and it is earned the Victoria Cross, which is bestowed on fleet commander Admiral Oshii.

It finally drives the US to rejoin the war, this time as Japan's ally, in the fight against Germany, which had launched a modified Operation Sea Lion against Britain on August 15, 1947.

To keep in line with the World War II theme, Konpeki no Kantai/Kyokujitsu no Kantai also features some characters who closely resemble actual historical figures from the 1940s, whose articles are linked.