The main character finds a mysterious book, and it is revealed that the main character's entire life is written within its pages, and that if they change the text within the book, the outcome of their life changes accordingly.
The main character finds a mysterious book waiting for them on their birthday, known as the Book of Memories; it is revealed that the main character's entire life is written within its pages, and that if they change the text within the book, the outcome of their life changes accordingly.