Arpeggio of Blue Steel

蒼き鋼のアルペジオ

Rising sea levels have swallowed much of the world's coastline by the early 21st century when an armada of hostile, sentient warships called the Fleet of Fog appears and blockades the oceans, crushing every navy that opposes it. Years later, former naval academy student Gunzou Chihaya commands the I-401, the first Fog vessel to defect to humanity's side, alongside its human-formed avatar Iona. The original manga remains ongoing and is the source material for the later anime adaptation.