Castle Oblivion
Castle Oblivion is the setting of Kingdom Hearts: Chain of Memories, and the only world the characters actually visit. It is controlled by Marluxia of Organization XIII
In Chain of Memories
Sora, Donald, and Goofy follow Pluto into Castle Oblivion. As soon as they enter, they forget all their skills, and are forced to use the castle's card-based combat system. The deeper they progress into the Castle, the more memories are reshaped by Namine. This is so that Marluxia and Larxene can use Sora as a puppet to overthrow Xemnas. The scheme fails thanks to Axel, and Marluxia and Larxene are killed.
Reverse/Rebirth Mode
Riku awakens inside the basement of Castle Oblivion, as a result of his connection to Sora. Here he faces his memories of both Xehanort's Heartless and Maleficent, and overcoming his fear of the darkness within himself. It was within the Castle that he meets DiZ and Namine, as well as reuniting with King Mickey.
Residents
Marluxia Larxene Axel Vexen Lexaeus Zexion Namine