Rosalyn is not the author of the book. Also, (this is just what I think) but the reason why both Rosalyn and Ella have the book when they “woke up” was because they both fell asleep with their phone on while reading the novel in their past lives. I hope this helps some bit. ヾ(❀╹◡╹)ノ~
I just don't understand so is rosalyn the author of the book? And how did They both have the book when They had their "reincarnation Wake up"