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