For me, it would be "Kimi to Yoru to Namida". I listened to the album in full a couple of times, but after a while I just began selecting the tracks that I wanted to hear repeatedly (like many people do with CDs). "Kimi to Yoru to Namida" was not one that I consciously chose to play. Then one day, I was walking through the London Underground, and "Kimi to Yoru to Namida" came on while I was waiting for a train. I listened to it, then realised that I hadn't heard it very much. Now I can't get it out of my head, and I listen to it every time I play Scandal. The part that has lodged itself firmly in my mind is when Haruna sings the word "yakusoku". Her voice sounds lovely through the whole track, but I particularly like the little break between "yaku" and "soku".
Are there any songs that grew on you over time?