The main problem with this anime is that it would go over most peoples heads with it's visual queues implying to the viewer what you could expect, maybe a psychological thriller? Something like Made in Abyss perhaps? This show IS to it's core and outer ends, a Slice-of-Life, it is in-fact, 2 girls all by them self in a seemingly life absent world, wandering around doing Slice-of-Lifey things. There is NO story. But you know what, that is what I like about this show.
The story itself could be just the moral, it's any way you paint it to be, and some people just choose to be negative and paint it as lost potential or boring, when you could paint it as a story of moral, teaching the value of everyday things we see in our day-to-day lives and take for granted. What exactly do these girls have? What do they make of the few things they do have? During the duration of the series I felt myself get excited over simple things, like when the girls got a hot potato, or finding rations amongst military equipment. It's truly a very interesting take on reality, taking a concept which could be used in a way people would expect it to, but then using it for something else, and executing it to tell a meaningful message, that is what I believe people overlook in this show.
The main point of the show, is the teach these hopeless girls how grim, and blank, the world can be, and to just accept that some things cannot be helped, to accept the reality that is the world they're in, and to get along with hopelessness. When you've failed, you can feel so carefree.
