Throughout the years we've gotten bits and pieces of KH information in its early days, usually in the Ultimanias. Some of the information is buried somewhere but does exist while there's some that doesn't seem to really have a source but has caught on through the fandom anyway. There was a KH trivia thread that had interesting little tidbits like how Kairi was originally just going to be called "Kai" but Nomura thought it too masculine so he went down a list until he found "-ri", liked how it sounded and just stuck it on and, Donald and Goofy were going to sing a song during the tutorial to teach Sora (and the audience) how to do stuff, and a male Disney counter part to each of the PoHs were supposed to go with Sora to help rescue them.
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That topic needs to be resurrected. ;~;