6v6の秘密のCD (6v6 no Himitsu no CD) is 6v6's second album. It contains 3 tracks, sung by GUMI and SF-A2 miki. It was first released at M3. A crossfade of the album can be heard on Nico Nico Douga. The official album website is available here. The album is purchasable on Suruga-Ya.