Rookie girl group One Piece is set to debut next year.

Yesterday, the last OST for the SBS drama, "Great Doctor" was revealed online.

The song, "Because it's You," is the theme song for Lee Min Ho and Kim Hee Sun's love line and was played during yesterday's episode. 

The track was sung by rookie girl group One Piece, who has not officially even debuted yet. 

The group was trained and produced by Vibe's Yoon Min Soo and group 4men in efforts to create a group that would 'make the world become one'.

The group has already had a few appearances on stage for various artists' concerts. They will officially debut next year.