Himegami Aisa

A quiet young girl with a rather blunt personality who wears miko attire. While she may seem normal, she is also known as "Deep Blood" and has the ability to kill vampires when they approach her, as her blood's smell attracts them. However, it made her miserable because, aside from sucking blood, vampires were just like humans. This prompts her to go to Academy City, hoping to find a way to get rid of her powers, until she meets the alchemist Aureolus Izzard. She cooperates with him because he told her that her blood can be used to save the life of a person he cared for (Index) in return for helping her get rid of her powers.

When Aureolus learns Index's life was already saved by Tōma and tries to kill him, Aisa attempts to defend Tōma, which prompts Aureolus to use his alchemy to try to kill her as she was now useless to him. Her life was saved by Tōma who dispelled the spell on her with his right hand. When she asks Tōma about why he saved her, he told her that he did not have a reason to rescue her. After the incident, she lives with Tōma and Index but later moves to Komoe's apartment and wears a magical power-blocking cross, stated to be a condensed version of Index's Walking Church, achieving her dream of no longer killing vampires just because they exist. She subsequently becomes a student at Tōma's school and is in his class. Ever since Tōma saved her life, Aisa started to have feelings for him, which is ironic as she once joked that Tōma's life was like a dating sim.