Heart Beat (feat. 송희란)
왜 나를 울려요 (Album ver.) This song was on the Daemul OST
악담 (Curse) This song was released February 7th as a digital single
Source: mnet, SoomieMusic, TheKp0palbums, TheKp0palbums, LuvBiRain9
The beginning of Heart Beat sounds exactly like another song. I can't remember the song's name but it's way too similar to be a coincidence. :\ I love Bad Girl though. It's nice to hear an upbeat song, as lovely as the ballads are.