He is sent to the prison "Abyss", only be saved by a "Chain" named Alice, who lives in the "Abyss" and is the Bloodstained Black Rabbit. They make an agreement: Oz needs to find the memory of Alice, and Alice needs to protect him and help him overcome the prison. When they return to their world, the time goes by ten years. They meet their friends and also meet their enemy. As the story goes on, they find out more about the mystery prison and the organization known as "Pandora".