Yume is a young girl living in a small village. She is the daughter of a mysterious woman who disappeared several years ago. Yume has been raised by her father, who works as a fisherman in the village. One day, Yume discovers an old book with strange powers. With this book, she can travel to different worlds and explore them. Along the way, she meets many strange creatures and learns about their customs and cultures. As Yume travels through these new worlds, she also discovers secrets about her mother's past and her own destiny.