Kingdom Hearts: Re: Chain of Memories

-This is the sequel to Re: Kingdom Hearts- After their first adventure in Re: Kingdom Hearts, Sora, Donald, Goofy and Penelope went to finding Riku and King Mickey. However, upon finding Castle Oblivion, Sora, Penelope and Riku (who is also in the castle), have three separate adventures. However, who is this Organization XIII and what are they planning? And who is Namine?