In a world in which each person has a Holy Grail that can summon a Servant, she is the only person without one. She meets the Boy, the last Servant summoned in the world.
From a young age, she has been possessed by evil spirits she calls “Dread Spirits". The spiritual illness, which she named Erlkönig, is a specialized weapon against Servants. It freely changes its shape and hardness to devour Spirit Cores.
Erice is neither a Pseudo-Servant nor a Demi-Servant, but rather a Quasi-Servant as she is a miracle child of a human male and a female Servant.
