I think this anime would be good without the cliche highschool girl fanservice. It's disgusting how they sexualize these 2 young girls throughout the series. It's supposed to be about survival. The plot is interesting, but it gets pretty boring and is very rushed. The only interesting character in this is the rifleman mask. Also, they really just throw you into the action too quickly at the beginning. They decided to reveal how she got there like 3 episodes later, I think it would've been more helpful for the first episode. I think some dubbed voice acting could be better. Doesn't catch my attention very well. Kinda cringe and LOTS of fanservice. Stopped watching due to the fact that it sexualizes young girls.
Overall: 2/5 stars (didn't give it one star because the overall plot is interesting). If you decide to watch this, good luck trying to stomach all the unnecessary panty shots and partial nudity of minors.