Spoiler alert: people have interesting thoughts and motivations and live/fight/die for different things.

Spoiler alert 2: shit happens, people die.

Um...that's literally the entire manga. I can't even make this shit up if I wanted to. I cannot understand how this received such high scores.

Sure, the characters were pretty interesting, and the premise of the story was pretty fresh, but the entire story was overwhelmingly repetitive. All the manga ever did was to repeatedly drill the 2 above spoilers into the reader's head over and over again using different characters as it killed them off one by one in predictable fashion (seriously I've never seen so many obvious death flags used in any manga ever). The plot was pretty much the most linear and predictable I've ever read, I pretty much saw the ending coming from a mile away.

If you understand the 2 spoilers I've provided above, then this manga has absolutely nothing more to offer you and I recommend you spend your valuable time elsewhere. This was 66 frigging chapters long and was an absolute waste of time.