Kingdom Hearts: Chain Of Memories.
The entrance to Kingdom Hearts is closed, devastating to the heartless and the attempt to restore the world to normalcy, but Riku and King Mickey are caught inside!
Sora, Donald, and Goofy, in looking for their companions came to the mysterious Castle Oblivion, where a person warned, "Ahead lies something you need, but to claim it, you must lose something dear."
What could be more precious than their memories of each other? And what do the shadowy members of Organization XIII wanted them for?