Hi, I know I reply this pretty late because I just found out that I had a lot of unapproved comments, but in order to unlock the true ending, you have to get the Pen item in the classroom in chapter 4, then you write a message on Adam's note near the swing in chapter 5. After that in chapter 11, you have to choose to let Nancy stay with her father. Then at the end of the game, you give Nancy in the real world her Bunny back. This will trigger the true ending.