I really liked the concept of this manga and the plot twist was amazing, even though I was expecting something different. I do feel like it would be more interesting if the characters were a bit older (around 13/14) because I feel they don't really act like an 11 y.o or more like they're too developed for an 11 y.o.
I also felt that the story dragged a bit but since this is the introduction of the story it might get more thrilling and I'm definitely gonna keep reading it.