Quote:In 2016, a catastrophe occurs after a nuclear meltdown from the nearby Odaiba nuclear power plant, contaminating Tokyo, forcing the government to order its citizens to evacuate the city. 20 years later, the city has become a ghost town due to the high levels of radiation and the government has banned entry for anyone. When a distress signal is received from Tokyo, the Self-Defense Forces dispatch 3 girls from the special rescue unit Coppelion to search for survivors. Due to genetic engineering, the Coppelions are impervious to radiation while also possessing special skills.

Quote:Due to global warming and rising sea levels of the early 21st century, humanity lost much of the Earth's landmass. At the same time, fleets of powerful sentient ships of unknown origin armed with advanced technology and weapons, known collectively as the "Fleet of Fog", mysteriously appeared and easily vanquished the world's naval forces. The Fleet of Fog impose a worldwide naval and aerial blockade, and thus preventing humanity from traveling across the seas.
In the year 2039, 17 years after the blockade, Gunzō Chihaya is a former student of the Japanese National Marine Academy and Captain of his crew, the Blue Steel fleet. The Blue Steel are infamous for possessing the only Fog submarine to have defected to the human side, the I-401 along its avatar Iona. Gunzō and his crew are hired by a faction of the Japanese government to deliver plans of a powerful weapon that may allow mankind to fight back against the Fleet of Fog to the United States, the only country that did not suffer from the blockade, thus capable of mass-producing it. However, the Blue Steel fleet faces obstacles not only from the Fleet of Fog and their human allies, but from other factions of the government with their own agenda, while gaining allies from both sides to increase their chances against such overwhelming odds.