An N type? I mean, he does a lot of crazy stuff in game. That would point to SP, wouldn't it? And he's obviously an introvert... so IS_P?
I don't really know if any of that is valid. Honestly, how is it possible to type anyone who literally says nothing? Where did you get N from?

It seems like a lot of people slap N on characters in movies/shows/games that they see as cool or something; or because of their actions (actions =/= thoughts). People also don't think that it could be an S using their N function.
I thought Sora was more INFJ; and I don't really recall Kairi having that much of a personality. But based on the little I saw, I'd say ISFJ.
I think that Riku before getting majorly mentally fucked up was an ISTP.
Other characters-
Donald- ISTJ
Goofy- ENFP
Mickey- ESFJ
I didn't see a lot of the other characters as having much of a personality to type (I don't mean the Disney and FF characters, since those are just Disney/FF characters and not really KH ones. I just put those three because they are main characters).