When Kingdom Hearts was released in North America and Europe, it received several updates that set it apart from the original Japanese release. The most noteworthy was the addition of a special battle with Sephiroth from Final Fantasy VII, which was accompanied by a startingly good - and as a result, incredibly popular - arrangement of Uematsu's famous One Winged Angel. However, this track, as well as another Shimomura arrangement of a track from Disney's Fantasia, was not featured on the Kingdom Hearts OST.
When Kingdom Hearts -FINAL MIX-, a new edition of the game for Japan including the NA and PAL updates as well as more cutscenes and battles, was released in Japan during Christmas of 2002, it came with a bonus cd featuring abovementioned tracks, and two new ones used in the game. Kingdom Hearts -FINAL MIX- Additional Tracks is that disc.