This book is actually a collection of my weird ideas. Because I have a lot of ideas, I just wrote about fast travel.
The first world: saving the poor stand-in
The second world: abandoned concubine in the cold palace x emperor
The third world: The Little Mermaid
The fourth world: Infinite Streaming (many of these worlds are just written as copies)
I personally like the first and third ones the best. If I have other ideas at that time, I can add a few more worlds to play with.
Concept: A collection of strange ideas