Secret's member Song Ji Eun released her solo single on 15th December and she will promote this song as a solo singer on various music shows very soon,meaning to say that Secret will stop promoting "I Want You Back " very soon.

Ji Eun teamed up with Hwan Hee for her new song "Yesterday" and the song is already topping realtime charts of various portal sites.

There are altogether two versions of this song,the duet version as well as the solo version,which you do you prefer??