I recommend starting simultaneously with the manga, with the second part is a very unique and original plot with high doses of graphic violence, nudity, comedy, social issues and puberty, the design, art and narrative totally follow the manga during the first first 90 chapters, is a great narrative for lovers of science fiction, weapons desgins, gore, relationships, eroticism and action.
The animation quality is very original mixing with 3d designers, the soundtrack and the music, especially the opening and closing themes are amazing, the main problem of the anime is the fast ending while the production catches the anime but only in the last 5 episodes that you can watch just for entertainment, a great message about the harsh nature of humans is also added with the narrative, the manga creator suggests creating some characters for the development of the protagonists. complementing the manga.