Riku finds himself well, sleeping, a world that is neither light nor darkness. He hears a strange voice, a voice that soon becomes Ansem’s voice. Ansem talks to Riku telling him many things…even to let him come back into his heart. Riku refuses and wakes. He is on the same road as Sora was on. He spots Castle Oblivion as well, because of his connection with Sora. He goes in, but starts working towards the ground floor from the bottom basement, him too working floor after floor defeating the figures of darkness from his memories to get to what he is searching for.
Vexen, an Organization member, makes a fake Riku that challenges not only Riku, but Sora as well, all over Namine. Because of this, Sora believes Riku to be turned back to darkness nearly the whole game. Riku progresses downward in the castle, and defeats, like Sora, many of the Organization members. Long story short, he eventually finds himself face to face with Ansem, and conquers.
He meets Namine, and sees Sora in his “hibernation”. The next we see of Riku, he is walking with King Mickey down that same long road in a long black hooded cloaks talking to an Organization member, DiZ, who has helped Riku and was actually the voice that he heard at the beginning of the game, not Ansem.
