This is seriously one of the most batshit synopses I’ve ever read:
Akikaze Cosmos is a regular elementary student who also helps take care of the hostel that her mom operates in the town of Hanami. She is incredibly responsible for her age and seems much more mature than the other older residents of the hostel, like the high school girl Soyokaze, the college drunk Sonoko, and the pervert Raita. Everything about this hostel and the town of Hanami seems normal except that everything outside of the town is a nuclear desert where no one is allowed to enter. But when Cosmos unwillingly wanders into the lifeless desert, she is somehow transformed into a magical angel.