I don't know if we could really judge Nanahoshi's reasons as dumb. She was not capable of magic so no plus for her. She has family that she wants to go back to. She lives in a peaceful country where morals between this world and her world differs greatly. She can't feel security. Also, she has...
I don't know why but this made me remember a time when my female classmates wrote notes and I joined them cause it looks interesting. They wrote, "for my future bf..." My innocent mind thought it meant best friend but I later realized after writing that bf actually meant boy friend. Now I know...