I only know the song 幸せの表現 (Expression of Happiness). The video is on youtube in VERY LQ (if anyone has a HQ version, would be very grateful if you could upload).
I found two other versions of the song, one sung by a guy and another by a girl, Erika. What I've gathered from Google Translate is that the idea was to have the song sung by a girl and guy's point of view with slight lyrical differences and that Erika was a rookie who won a competition and got to make the third version. So what was Gaball? How long did they last for? Who is Joanne? And is just me or is she singing this song with a Korean accent?