PTSD after first kill. Yeah, you are not a psychopath. And also that's not being weak, that's called having a moral compass AKA humanity.
Didn't expect her to fight Mimi and go to the battlefield in the same chapter tho. I'm glad she returned! (Also, it's cool that no one it's complaining about them kissing so out in the open)
Having said that, in the last panel I kinda get the feeling this girl convinced the other to go to war instead of her. I hope I'm wrong and she decided that out of her own will. Anyway, the contrast between them and Shiina/Mimi it's really interesting.