Girl group T-ARA was joined by new member Ahreum for her first performance on "Music Core."

On July 6, T-ARA's agency, Core Contents Media, revealed photos of T-ARA members along with Ahreum preparing for the pre-recording session.

The photo shows the members' fun and silly expressions as they introduce their newest member Ahreum.

T-ARA's comeback performance includes the song "Don't Leave," which was incorporated in the music video of "Day By Day."

The song "Don't Leave," written together by songwriters Cho Young Soo and Ahn Young Min, escapes the typical ballad image to show a brand new concept.

T-ARA will be seen on stage of "Music Core" with an orchestra consisting of 70 members, which is truly a rare sight for an idol group.

Following their ballad, "Don't Leave," T-ARA will perform the title song, "Day By Day," with choreography done by world-famous choreographer Jonte Moaning.