The anime namesake and the main female lead, Shion is tasked with hunting down and killing Geists. Yet when she is saved by the Geist infected Hiroki she returns the favor and tells Hiroki that she will not kill him for now because he has a strong heart that is able to resist the Giest. Shion eventually falls in Love with Hiroki.
She dies at the end by Infinity. Infinity claimed that he was "built" to kill the Wolf Giest.