Arpeggio of Blue Steel -Ars Nova-

By 2039, rising seas brought on by global warming have swallowed vast stretches of land. In the aftermath, an overwhelming armada known as the Fleet of Fog appears and crushes the world’s naval forces with advanced weaponry. Each vessel is guided by a “Mental Model,” a humanlike avatar tied to the ship’s Union Core, and though their personalities differ, they all obey a mysterious directive called the Admiralty Code. The Fleet of Fog enforces a blockade that cuts humanity off from crossing the oceans.

Seventeen years later, National Marine Academy graduate Gunzou Chihaya encounters the submarine I-401 and its Mental Model, Iona—who, for reasons unknown, chooses to support mankind. With I-401 as a rare advantage against the blockade, Gunzou and his friends take up the name Blue Steel and set out as privateers on a perilous voyage with the hope of changing humanity’s fate.