@Danbaby when they were inside the book or let's say their first lives, huimin drew some sketches. Their second life was totally based on huimins sketches and everything worked according to it. The last sketch that huimin made was watching sunrise on new year, in the year when they were in college. Iheon knew that and also that that world would disappear after the scene in the last sketch is fulfilled. So he indirectly made huimin read the book in hopes that even if that world disappeared, they would go back to the world of the book again and that's exactly what happened.
I only want to live in fantasy, I don't like the real world..Yes, you're right, I think I have mental disorder too. So what, there's no sane person here. That's why I'm here.