Justine is not a terribly good role model. She teaches Ali how to memorize produce codes and bag groceries, but also how to purge to stay thin and how to shoplift from stores. Apathetic and bored with her own life, Ali doggedly follows Justine's example in every way. It ends badly and on a tragic note.
This is a very short story (135 pages, nearly half of which are illustrations) and a quick read. It's not really a story per se, but more a series of journal entries, with ink line drawings of common everyday objects (a Coke can, a bag of potato chips, a gas station sign. etc.). The banality of the drawings and the story itself is part of its charm. Ali's life isn't particularly big or important to the world, but it is a complex swirl of emotions and feelings for Ali herself, most of which she is unable to process or contextualize. It's a tragedy, but not one that Ali really cares much about.