The countess of blood that became the model for the vampire Carmilla. ..or it should have been, but what was summoned as a Servant was her 14 year-old self from before she had committed any crimes. A sweet-type Servant who calls herself an idol. Noble, high-handed, cruel, merciless - she displays inhuman manners just like in legends.
An anti-hero of evil, but she herself is a young girl that dreams of love. Her timid nature is her own ruin: as a consequence of it, she helps her comrades and overlooks her enemies, and thus ends up displaying human goodness that places her on the borderline of "well, you could even call her a Heroic Spirit". "Could it be that you're actually a good person?" - she herself hates to be referred in such a manner.