memories end
In his search for Riku and the King, Sora steps foot in Castle Oblivion. As soon as he does, he begins to forget; who he is, his life, his friends. His reason for being there in the first place. The Castle is controlled by cards; cards of his memories, none the less, as he travels again to the world he helped during his first adventure. As is pointed out to him by one of the mysterious black robed Organization member's..
As Sora climbs further, he encounters three of the members of the Organization: Larxene, Axel, and Marluxia. And.. also, Namine. A girl Sora begins to believe is Kairi.. the girl he cares about the most. In fact, Namine has an ability to re-weave Sora's memories, so he thinks Kairi is her. Axel, however, tells Namine to choose by herself what to do. Namine chooses to tell Sora the truth. As he reaches the top floor, he chooses his old memories over the fake ones. Thus, he is put to sleep.
Meanwhile, Riku has also entered Castle Oblvion, and has encountered three other Organization members. Zexion, Vexen, and Lexaeus. After fighting with Ansem, he reclaims his heart as his own, and with DiZ and King Mickey at his side, he encounters a crossroads. He chooses to take the middle road. That is, 'the road to dawn'.