I'd imagine that her father has been dead since she was 6, causing her obsession with death as a coping mechanism. Her mother works in an office, and is away often, but doesn't mind her daughter's morbid behavior. She has an older brother named Shoto, who is away often with a group of troublemaking "friends". She loves her brother very much, but doesn't know how to help him, since he has a hard time listening to her.