Protocol RyuGu

In near-future Earth, a new Ice Age has taken hold—and after a world war, the winners cling to what few non-frozen paradises remain on the surface, while the losers dwell under the sea and begin to evolve into something else. But once these undersea survivors obtain a new, unheard-of flying craft, will they manage to rule over the planet once more?

(Source: K MANGA)