Here's an explanation full of spoilers. Chie (the one with braids) and Saho (the one with short hair) are twins, but one of them died. The first chapters present us Saho as the surviving twin, in them she meets a ghost (Chie) and discovers that this girl was her sister who had already died. But in the following chapters we find out that what we saw were fragments of Chie's dreams and, in fact, she is the one who is alive. Chie feels guilty about her sister's death and the dreams were attempts she made to communicate and apologize. Saho appears with white hair during Chie's dreams and in the apparitions as a ghost in the real world, but in photos and real memories she appears with dark hair. During the most part of the story we see Chie communicating with the ghost of her sister, but we discovered that these conversations were actually hallucinations and that she was never able to see Saho as a ghost. The story basically shows how Chie deals with the guilt and mourning for her sister's death, she projects much of her anger on her parents and search in other people traits that fill up the lack that Saho makes in her life.
Here's an explanation full of spoilers. Chie (the one with braids) and Saho (the one with short hair) are twins, but one of them died. The first chapters present us Saho as the surviving twin, in them she meets a ghost (Chie) and discovers that this girl was her sister who had already died. But in the following chapters we find out that what we saw were fragments of Chie's dreams and, in fact, she is the one who is alive. Chie feels guilty about her sister's death and the dreams were attempts she made to communicate and apologize. Saho appears with white hair during Chie's dreams and in the apparitions as a ghost in the real world, but in photos and real memories she appears with dark hair.
During the most part of the story we see Chie communicating with the ghost of her sister, but we discovered that these conversations were actually hallucinations and that she was never able to see Saho as a ghost. The story basically shows how Chie deals with the guilt and mourning for her sister's death, she projects much of her anger on her parents and search in other people traits that fill up the lack that Saho makes in her life.