"Musique pour la tristesse de Xion" (Fra: "Music for the sadness of Xion") is a musical piece composed by Yoko Shimomura that is used in Kingdom Hearts 358/2 Days and Kingdom Hearts HD 1.5 ReMIX. As its name implies, it is Xion's theme.
The theme plays when examining the statistics on the Illustrated Xion [EX] medal. If the player shares the medal for use by fellow party members, their home screen music will be changed to this theme.
"Musique pour la tristesse de Xion" is approximately three minutes and fifty-eight seconds long (referencing Kingdom Hearts 358/2 Days), [KH Days] and the piano collections version five minutes and thirty-five seconds long. Regardless of the source, the entire piece has a time signature of 4/4 time. The original in-game version plays at a tempo of 55 beats per minute. The piano collections track takes more freedom with both the tempo and interpretation, though the common tempo is 50 beats per minute.
In the Kingdom Hearts 358/2 Days version, the first fifteen measures of the piece are written in the key of G Minor and then transition into the key of Eb [E flat] Minor. The piece has a brief introduction of two measures, lasting around nine seconds, then leads into the repeated melodic section which lasts for twelve measures, and is followed by a transition into a new phrase that lasts for sixteen measures, before repeating back to the first phrase, allowing for smooth transitions between loops. The instrumentation for the original version and HD remake includes: piano, orchestral bells, synthesizer, and strings.
In the piano collections version, the seventeen measures are in the key of C Minor. Beginning in measure eighteen the key switches to Ab [A flat] Major and lasts until measure thirty-two, then transitioning into the key of Gb [G flat] Major.The next section of the piano collections version contains a rendition of "Vector to the Heavens." Xion's original theme is revisited again though in measure sixty-eight and continues to till the end of the piece. This final appearance returns to the original key of C Minor.
The piece is characterized by a moving eighth note pattern in the introduction in the treble clef part (in-game versions) or bass cleft (left hand, piano collections version). The main melody's rhythm is a trade off between a dotted quarter note and an eighth note, making the melody follow the rhythm of "1- and 3- and." The piece is played in the lower spectrum of dynamics, with the only true "louder" section occurring during the "Vector to the Heavens" portion of the piano collections version.