Aoki Hagane no Arpeggio: Ars Nova

In the year 2039, global warming has caused a sudden rise in sea level, leading mankind to lose a great deal of land territory. At the same time, a fleet of mysterious warships clad in mist, known as the "Fleet of Fog," begin to appear throughout the world's seas, attacking humanity's warships with their powerful superweapons. Humanity threw all the military strength it possessed at the Fleet of Fog in a decisive battle, but was crushed by the fleet's overwhelming might...