Kingdom Hearts The Secret Place

It's Ansem! Xehanorts heartless! At the end when you're about to fight him he says "So you have come this far and still you understand nothing! All hearts return to DARKNESS!" or something like that. At the begining in the secret place he says that Sora knows nothing and understands nothing- and it's the same voice. When your at Hollow Bastion and there's a cloaked figure talking to Riku, thats the same dude as the one in the secret place and he is Xehanorts heartless!

 

Usually developers plan out the whole series of games by the first game that is released.