Disney does own Kingdom Hearts. Sorry to burst everyone's perfect Square Enix bubble, but there are 3 undeniable pieces of evidence for this conclusion:
1.) Trademarks. Taken from KH2 site:
© Disney Enterprises, Inc.
Developed by SQUARE ENIX.
© Disney. Tim Burton's The Nightmare Before Christmas © Touchstone Pictures. Developed by SQUARE ENIX. Characters from FINAL FANTASY video game series: © 1990, 1997, 1999, 2001, 2002, 2005 Square Enix Co., Ltd. All Rights Reserved. SQUARE ENIX and the SQUARE ENIX logo are trademarks of Square Enix Co., Ltd.
For those who suck at interpreting walls of legal tex, the primary trademark is always listed first, and it's Disney Enterprises. In fact, Square Enix has no trademarks relating to the game. They are given credit for development, but the only intellectual property they are credited for are their own FF characters and logos.
2.) Every character and villian in the Kingdom Hearts series including every original character is owned by Disney. Proof http://www.gaming-age.com/cgi-bin/previews/preview.pl?sys=ps2&game=kingdomhearts
Four new DISNEY main characters make their debut in KINGDOM HEARTS: Sora, Riku, Kairi and the Heartless.
3.) Disney has already made a Kingdom Hearts game without Square. Kingdom Hearts V-Cast was made without any involvement or consent from Square Enix. All Disney had to do to make this game was remove FF characters.
So yeah, in conclusion, there is no debate about who owns Kingdom Hearts. It's Disney. Saying Square owns KH or even any rights to KH is like saying Retro owns Metroid. Square was just used as a tool by Disney for their development. Would Kingdom Hearts be good without Square Enix? Probably not, but it could be made without them nontheless. They certainly have the upper hand in any discussion about development platforms.
