Both versions of the song contain reversed lyrics, voiced by Utada herself. The reversed lyrics are in English in both versions. They include; "My heart's a battleground" which is played in English even in the Japanese version of the song. The reversed portion of the songs are "I need more affection than you know"; in the "battleground" section, "So many ups and downs" and "I need true emotions" are the two other examples of the reversed lyrics.
"Passion" is the original, Japanese version of "Sanctuary"; it was originally released on Utada's Ultra Blue album. "Sanctuary (Opening)" was released on the album This Is the One as a bonus track.
At the end of Kingdom Hearts II, Kingdom Hearts 358/2 Days, and Kingdom Hearts 3D: Dream Drop Distance, two different versions called "Sanctuary (Ending)" (English) and "Passion ~after the battle~" (Japanese), are used. These versions are much quieter for most of the song until the ending part of it, which use a faster instrumental than the rest of the song.