Utada's 21st single: Prisoner of Love is used as the theme song for recent series Last Friends, which i have been boasting about lately, if you've missed it, then i don't know what's the problem, either your eyes needing a checkup or something...*joking*

The single consists of 4 tracks:

Prisoner of Love (Original Version)
Prisoner of Love (Quiet Version)
Prisoner of Love (Original Version-Karaoke)
Prisoner of Love (Quiet Version-Karaoke)

Basically, they're the same song, really xD

The original version offers a more upbeat track, together with the intense violins, and also her backup vocals really work well here indeed.

Whereas the Quiet Version only features her piano, vocals and violins. It's well, the quieter version, make it simpler, and it exudes more expression for some reason. A more mellow version of the original piece.