An honored guest of the Ryudou family, permitted to live at their temple until the preparations for her marriage have been finalized. A gorgeous and talented yet mysterious woman of high stature, her presence has attracted the attention of many trainee monks.
Caster is a heretic who has made a personal enemy out of Tohsaka due to her draining the townsfolk of mana and nearly killing them in the process. She is ruthless, talented and determined. Assassin guards the gate of her base of operations and is her Servant. Despite this, she shows a level of interest in all of the protagonists and desires to take Saber for her own.
Caster is one of the physically-weakest Servants and relies mostly on her powerful anti-Army magic, her Territory Creation skill and her skeletal golems when fighting her opponents. She does less well in single combat.
She was Medea in her past life.