Two storylines. One: girl transported to world in exchange for her sisters life. (I always wonder about the people left behind in this situation -- the parents wouldn't want her giving her life up like that). Two. Goddess who is missing after her magical item was stolen. People (and their descendants) who stole it are forever cursed. (That seems a bit harsh).
How are the two linked? Reincarnation? Who is God really?
Boxed Garden