Kyouko Mejiro lived a normal life until she met Nazuna Nanakusa during night school, where the two formed a close friendship. Kyouko was unaware that Nazuna was a vampire at the time, but upon discovering the truth, she remained accepting until tragedy struck on her eighteenth birthday.

That night, her father who had secretly been turned into a vampire attacked her and her mother. Kyouko was forced to kill her own father in self-defense, but not before her mother was murdered before her eyes. This traumatic event shattered her trust in vampires and scarred her for life. Kyouko came to believe that Kiku Hoshimi, the vampire who turned her father, was responsible for the destruction of her family.

Vowing revenge, she abandoned her former identity and took on the alias Anko Uguisu, becoming a private investigator specializing in vampire-related cases. Over the next ten years, she trained herself to track, expose, and eliminate vampires, eventually becoming one of the few known humans capable of killing a vampire.

As Anko Uguisu, Kyouko maintains a sleek and composed look: she has straight black hair, often tied in a ponytail or left loose, and sharp, calculating eyes that reflect her cold resolve. She typically wears dark clothing, often resembling a trench coat or professional detective attire, blending into the shadows of the night she operates in.

Her demeanor is serious, and her posture rigid, always on high alert. Despite her relatively young appearance, her presence is commanding, making it clear she is both intelligent and dangerous.

Kyouko is intensely driven, highly intelligent, and emotionally guarded. As Anko, she presents a cold, cynical front, with a dry sense of humor and a no-nonsense attitude. Her experiences have taught her to mistrust others, especially vampires, and she frequently uses manipulation, interrogation, and psychological tactics to achieve her goals.

However, beneath her hardened exterior lies a deeply wounded soul. Kyouko is burdened by grief, survivor’s guilt, and the hatred she cultivated as a means to cope with her past. Though she sees herself as a hunter, her actions are motivated by fear and pain as much as by justice.

Kyouko is not completely without empathy. Over time, especially through her interactions with Kou Yamori, she begins to question her black-and-white worldview, leading to emotional vulnerability and eventual redemption.

• The Detective Appears
  Kyouko enters the story under her alias Anko Uguisu, tracking vampires and investigating Nazuna’s connection to Kou. Her presence introduces a more grounded, psychological threat to the supernatural world, as she investigates vampire activity and challenges Kou’s romantic ideals.

• Clashing with Nazuna and Kou
  Anko’s investigations lead her to confront Nazuna, whom she still resents for their past. She threatens to kill Kou if he refuses to abandon the vampire lifestyle. Kou, however, intervenes not only to protect Nazuna but also to understand Anko’s pain. Their clash culminates in a Halloween showdown, where Anko, cornered and emotionally overwhelmed, attempts suicide only to be saved by Kou.

• Redemption and New Purpose
  After the failed suicide attempt and Kou’s sudden partial vampire transformation, Kyouko’s perspective shifts. She reclaims her identity as Kyouko Mejiro and begins working with Kou and Nazuna to uncover the mystery of his hybrid condition. Though still wary of vampires, Kyouko slowly transitions from hunter to ally, choosing to help understand rather than destroy.