Ciel is a pivotal character in the visual novel series Tsukihime, created by Type-Moon. She is initially introduced as a cheerful and friendly student at Shiki Tohno's school, but her true identity is far more complex. Ciel is an executioner for the Church, tasked with hunting down vampires and other supernatural beings. Her mission leads her to investigate the events surrounding Shiki and the mysterious vampire Arcueid Brunestud. Despite her serious duties, Ciel often displays a playful and teasing demeanor, adding depth to her character. Her complex relationship with Shiki and her hidden past are central to the narrative, making her a key figure in the unfolding story.