Kouhei Morioka, a freelance photographer with a fascination for the supernatural, travels to a remote German castle to investigate rumors of paranormal activity. There, he encounters Hazuki, a young vampire girl who claims to be a princess of the Shuzen family, a powerful vampire clan. Hazuki attempts to bite Kouhei to turn him into her servant, but her powers fail due to a mysterious curse. Despite her initial hostility, Kouhei rescues Hazuki from the castle and takes her back to Japan, where they begin living together.

As the story progresses, Hazuki’s presence attracts the attention of other supernatural beings, including her estranged family members. Her younger sister, Seiji, and her half-sister, Elfriede, both harbor their own agendas regarding Hazuki’s return. The Shuzen family’s patriarch, Count Kinkel, seeks to reclaim Hazuki, while Elfriede, who wields significant influence within the family, views Hazuki as a threat to her own ambitions. The narrative explores the dynamics of the Shuzen family, their internal conflicts, and their interactions with humans.

Kouhei’s life becomes increasingly entangled with the supernatural as he protects Hazuki from various threats. Alongside his cousin, Hiromi Anzai, who runs a detective agency specializing in occult cases, Kouhei navigates the dangers posed by vampires, werewolves, and other entities. Hazuki’s character evolves as she grapples with her identity, her curse, and her growing attachment to Kouhei. The curse that prevents her from fully embracing her vampiric powers becomes a central plot point, with its origins tied to her mother’s tragic past.

The series blends elements of comedy, romance, and supernatural intrigue, with a focus on the evolving relationship between Kouhei and Hazuki. Their bond deepens as they face external threats and internal struggles, culminating in a confrontation with the Shuzen family that forces Hazuki to confront her destiny. The narrative balances lighthearted moments with darker themes, exploring themes of family, loyalty, and the clash between human and supernatural worlds. The story concludes with resolutions to key conflicts, though it leaves room for the characters’ continued growth and the lingering mysteries of their world.