I'm going to go little too deep about the back story but here it goes.
The little girl is running from death because of what happened to those around her. Hence why she lives alone in a small home. She is running from her own death. Her life is a nightmare not her dreams. The girl first goes through denial. "It's a dream." Is her denying the truth of her fate. Next she goes through Anger. Which is symbolized by the enemies and obstacles. The girl takes out her anger on the creatures. The third stage of the Kübler-Ross model of grief is symbolized with the shop. She bargains to get through it. Depression is symbolized by when she actually gets captured by Death. The girl lets it overwhelm her. Finally we reach the last stage. Acceptance. She has finally gotten enough strength ("upgrading" in this instance) to accept her fate.
-Sir Logan with a really long post.
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