The Other Promise is a orchestra based song. It has a sad melody to it. It is used as Roxas's theme song. The sadness of the song reflects on Roxas' confusion and lonliness. Until he meets Xemnas Roxas doesn't remember his true name (which would be Sora). This song also played in Kingdom Hearts II: Final Mix as the battle song as when you fight Roxas as Sora.
Final Occurance
This song played for the final time when Sora fought Roxas in his vision.