The Old Book is a relic that transports its reader into the world of 100 Acre Wood. Although it is featured in several games, the book is only an obtainable item in Kingdom Hearts. Torn Pages are often ripped out of the book, removing areas from the 100 Acre Wood.
Kingdom Hearts Birth by Sleep
In Radiant Garden, Merlin accidentally drops the old book on his way home. Terra picks it up and delivers it to Merlin, but he claims to have never seen the book before. Afterwards, Merlin decides to keep the book in his house and allows Terra to view it at any time. Later, Merlin extends this permission by allowing Ventus and Aqua to see the book too.
While on his second visit to Traverse Town, Cid asks Sora to deliver the old book to Merlin. After it is delivered to Merlin's House, Merlin explains that the book has pages torn out that have been scattered across the worlds. Merlin leaves the book in his house and allows Sora to look at it at any time. Over the course of his journey, Sora eventually retrieves all of the torn pages and puts them back in their rightful place.
Kingdom Hearts II
Merlin takes the book with him when he moves to live in Hollow Bastion. A group of Heartless attempt to steal the book but they are handled by Sora. Unfortunately, pages are torn out during the fight and they are scattered across the worlds. This affects Winnie the Pooh, one of the book's inhabitants, as he becomes a victim of amnesia. During his adventures, Sora manages to find the missing pages and mends the book, curing Pooh's lost memories.
Kingdom Hearts Chain of Memories
The book appears as the world icon of the Hundred Acre Wood.
Finding and retrieving torn pages unlocks new areas of the 100 Acre Wood. In Kingdom Hearts, each area unlocked from a torn page contains a mini-game that offers a reward. Additionally, completing every page is required for Sora to be able to lock the world's Keyhole.
Kingdom Hearts II