One day an Avid Reader for some mysterious circumstances get transported in a dimensions full of books and then he heard a voice from behind him.
•} Hello Human, I'm the constellation of Stories and I ask of you to fix or continue this unfinished stories {•
So the Idea is simple, an avid reader gets transported to a dimension of a constellation. Now the premise of this story is that person is going to be transported to a story and basically finish it by either surviving it or concluding it in a satisfying ending.
So he's going to be given three choices every round and every time he completed the story his power in there will remain in him after exiting the story.
That's basically it, I got inspired from SSS Class S*icide Hunter and that one novel who's tittle I can't remember anymore, it's where the Protagonist goes through different settings of stories just to save the misunderstood Villainess.