Attack on Titan is one of the most brutal series I've seen. Ok, not really but there's a lot of "fighting for survival" tone in it.
Again, not going to spoil it but the main plot is that humans are terrorized by these giant, humanoid beings called "Titans" which eat people just for fun. The titans can't even digest the people they eat because they lack proper digestive systems and it's an unexplained mystery why the titans do as they do.
Humans have built giant walls around their villages but the titans still break through from time to time, absolutely devastating the people when they do. Most of the humans' efforts are devoted to fighting against the titans.
Our main characters are motivated to train and fight against the titans when the main protagonist's mother is torn in half and eaten by one of the titans. This burning hatred drives him and eventually leads to something much stranger and hard to explain than the mere desire to fight.
Oh god that was hilarious. That girl eating the potato was actually like that in the show, too. Just sort of a dumbass who didn't know how to behave. It was one of the few pieces of comic relief in the actual show.
It doesn't matter if the glass is half empty or half full. There's clearly enough room for more wine.
I kind of stopped following the manga after a while, but it's a good series. It's a lot of fun, overall, the 3D maneuver gear are a neat concept, if likely impossible in practice. The show does a really good job of following the original manga, to the point I actually stopped watching it after a point because I'd already read it.