Arpeggio of Blue Steel Vol 16

Arpeggio of Blue Steel by Ark Performance. An Action manga rated Teen, published in English by Seven Seas.

Humanity has lost control of the oceans to the Fleet of Fog, a mysterious armada of warships with advanced technology. Young captain Gunzo Chihaya teams up with Iona, the humanlike avatar of a Fog submarine who has defected to humanity's side. A naval sci-fi action series.