Edit: apparently this is a very common form of Japanese storytelling called an isekai. There are 8 billion people in this world, no idea can be original. And sometimes you miss out on things many other people know. I’m clearly one of today’s lucky 10000.
So you would assume you’re in a story. Interesting. If it happened to me, I would first think I’m dreaming, then the real world. But I wouldn’t think I was in a story.