Prologue.
The Letter in the Bottle
Sora, Riku, and Kairi,
Hey fellas. I never had the chance to thank you properly for saving the worlds so that's first. Thank you so much. Trillions of people are forever in your debt. But there is also bad news. Due to the defeat of both "Ansem" and Xemnas, Xehanort has come back. Also, there were three keybearers that fought him 11 years ago. They are Terra, Aqua, and Ventus, or Ven for short. Xehanort had taken over Terra's body, but Terra has been reborn and is living with me in Disney Castle. Aqua is trapped in the Realm of Darkness but has fount the Door to the Light. However, only a Princess of Heart is able to open the Door. And Ven is trapped in Castle Oblivion, and only Aqua knows where in the Castle. So I must graciously ask of you to help us defend the worlds one more time. First off, two of my colleagues will be picking you up on July 14th. Then you will head to the world of Luminatio. On this world resides the Door to the Light, and now, Castle Oblivion. After this, all of you will return here to Disney Castle ( I really want to tell you as much as possible, but I can't due the fact that this letter could get intercepted, and I must be careful.)
Sincerely,
King Mickey Mouse
P.S. Sora, and Riku, you need to train Kairi for what lies ahead. So I leave it to you. See ya soon.