Ciel

Ciel is first presented as a senior attending the same school as the main protagonist Shiki Tohno, where she is the president and only member of the tea ceremony club, and also good friends with Arihiko Inui, Satsuki Yumizuka and Shiki himself. Her outward demeanor is that of a calm, friendly, and peaceful person. However, Ciel's true character is later revealed as the story progresses.

She is a member of the Burial Agency, a secret organization within the Catholic Church made up of skilled assassins, feared even within the Church itself, known for showing no mercy and willing to do whatever it takes to get their task done even to the point of using forbidden magics and creatures. Her objective in Tsukihime is that of hunting down the heretic vampire Roa, which while being a direct order from the church is also her own vendetta. In Melty Blood she has been ordered by the church to hunt down Roa.