Zlata is essentially two different people during the course of this book. There is the Zlata that we meet in innocence, who is a normal preteen girl who likes music and hanging out with her friends. Then, because of the difficult fate of war, her life is uprooted. She can't go to school anymore, because the enemy has selected them as their targets, so they are especially dangerous. So, she studies alone, with no friends, in a basement with rats. Without a doubt, Zlata goes from innocence to experience during the book.
This is a transition that happens more naturally later in life, but Zlata is forced into survival mode young in life, before her full maturation and adulthood, so she uses her diary as a sacred tool. By writing what experiences are happening to her, she can catalog difficult or overwhelming fears and emotions. Plus, writing down what she's thinking is like explaining herself through a problem, so this novel is essentially that process being demonstrated.
With a family who loves her, because they are all committed to helping one another, their sacrifices are done willingly, and they do suffer tremendously, but it isn't as bad as it could be otherwise, since they are not alone. In either case, Zlata is lonesome in other ways—her parents simply will not understand what these events are really like in the mind of a young person, so Zlata shares her thoughts with herself by writing. Writing is a tool that she uses for mental health.
