Diva (ディーヴァ ,Dīva?), Saya's younger twin sister and the main series antagonist, the greatest sworn enemy of the Red Shield. Like her sister she is a pure chiropteran Queen. She was raised in complete solitude inside a decaying tower, located in the ruins in the grounds of the Zoo - following her release she attacked everyone at the château where Saya lived. Red Shield was formed soon afterwards.
Like Saya, Diva appears to be a 16-year-old girl, but is actually 174. Although she and Saya are twins, Diva possesses a more Caucasian look compared to her sister's oriental one. Diva has long, waist-length black hair, pale skin, and blue eyes. When her full debut was made she also wore a white dress and blue ballet shoes. With the result of her attack on Riku, she changes her physical appearance to resemble Riku and retains that apperance until her final battle with Saya. Also, Diva is tall and lithe, standing at least 5"8"(5 feet 8 inches approx.) and weighs no more than 89 lbs (40.5 kg)
During one of Amshel's visits, after waking up from her hibernation, her hair reached floor-length. Diva's most unique trait is that her eye color changes from blue to an intense sapphire ruby blue when she feeds from blood or enters into battle.
Diva is essentially a child, with a psychopathic streak of selfishness. Although she and Saya are twins, Diva is often referred as the younger sister due to her immature nature. Unlike Saya, Diva is sadistic, killing for pleasure rather than duty. By 2005, when Blood+ begins, Diva has five living chevaliers, who head up the Cinq Flèches Group. She giggles after killing people, shows little reaction to the death of her own chevaliers, and tends to destroy things when bored. Diva seems to enjoy tormenting Saya and frequently says she wants to kill her.
Her personality is the combined result of neglect and being raised by Amshel. Prior to being released from the tower she inhabited for 50 years Diva could not speak, instead communicating telepathically with her sister. Just before Saya opens the door Diva mentions that she is scared, despite being asked to be let outside. This is the only sign of fear she ever mentions throughout the series. Despite this she remains expressionless - showing no surprise when Saya opens the door and no joy when killing the people at the Zoo.
As a result of her attack on Riku, Diva becomes pregnant. She does not give birth for over a year, when Amshel cuts the cocoons out of her body. At the Metropolitan Opera House, Diva is set to perform a live broadcast which would cause a large portion of the world's population to turn into chiropterans. The Red Shield and Saya are able to stop the broadcast, and the sisters have their final battle while Diva's chevalier Nathan watches nearby with the babies. The fight ends as Diva and Saya pierce one another with their swords, which each had coated with their own blood. Saya is unharmed by the attack due to Diva's blood having lost its power when she became pregnant. Diva begins to crystallize from the effects of Saya's blood. Her babies emerge from their cocoons and Diva reaches for them, imagining herself with her daughters and smiling at the vision before dying.
Opinion regarding Diva changed dramatically throughout the series. At first she was seen as an interesting and sympathetic villain, having been locked away for most of her life while Saya was allowed to be free. These feelings however took a sudden turn following the rape and death of Riku. This shocked fans and decreases a little feeling towards her - many believed her actions were unforgivable.
However her reaction to her unborn children gained back equal, if not more, interests in the character. Diva showed an unknown motherly and loving attitude towards them she had not show to anyone else, including her own Chevaliers. Like Saya, her personalty changed once she learned to love someone else. The viewers then began to regard her with more pity, as she had shown what lengths she would go to in order to get a family.