"Sai's Picture Book!!" (サイの絵本!!, Sai no Ehon!!) is chapter 300 of the original Naruto manga.
While taking a break with Orochimaru and Kabuto, Sai finds he is missing something. Sakura, Naruto, and Yamato elsewhere look at Sai's picture book. At opposite ends of the book appear to be Sai and his brother, who fight various opponents and whose stories meet in the middle of the book. The centre is incomplete. They keep moving, just as Sai reaches Orochimaru's base and meets Sasuke.