These are DVD specials, which include some extra footage and music videos;
Character DVD #1 - Midori & Reika
Character DVD #1 - Midori Music Video
Character DVD #1 - Reika Music Video
Character DVD #2 - Futaba & Chigusa
Character DVD #2 - Futaba Music Video
Character DVD #2 - Chigusa Music Video
Character DVD #3 - Sanae & Wakaba
Character DVD #3 - Sanae Music Video
Character DVD #3 - Wakaba Music Video