According to the sheet music published at Musicnotes.com, the song is written in the key of B♭ major and is set in time signature of common time with a tempo of 84 beats per minute. Utada's vocal range spans between the notes G3 to G5, specifically between the chorus lyrics; "When you walk away / You don't hear me say / Please oh baby don't go / Simple and clean is the way that you're making me feel tonight / It's hard to let it go".