Suisei no Gargantia

Synopsis

Ledo starts his offensive on the whalesquid nest, assisted by Pinion's crew and their barrage of depth charges, obliterating the enemies without much effort. While investigating an ancient facility, Ledo finds some records and upon accessing them, he learns that the Hideauze were once humans who underwent heavy genetic modification to adapt themselves to space environment, calling themselves "Evolvers". Viewing their efforts as blasphemy, a faction of mankind declared war on them, leading to their current conflict after both sides abandoned Earth during the fifth ice age, except for the ancestors to the current humans and whalesquid living on the planet. Devastated by this revelation, Ledo shouts in despair when Chamber slays a Hideauze (human sized) child without his permission. Back at the Gargantia, both Bebel and Amy show signs of how much they miss him.

(Source: Wikipedia)