SS501 came up with Rainbow's name?

Girl group Rainbow, currently promoting their first mini-album "Gossip Girl" with the track "Not Your Girl," had a few things to say about SS501. The girls revealed on an interview with Arirang that they had originally had a different name for the group, but Kyu Jong from SS501 thought the old name was too difficult and suggested that the group be named Rainbow. It makes sense of course with the seven members and seven colors in the Rainbow. During the interview, the girls were also asked whether they had a special relationship with Kara and SS501 (all three are from entertainment company DSP). The girls answered that one of them had featured in the "Love Like This" MV. Who was it? Watch the video below and find out: http://www.youtube.com/watch?v=mIR6DUtIaEU