Kaoruko Mochizuki runs an herb shop in a small seaside town. One day, a mysterious man dressed in black named Kaname Hibiki enters her shop and reveals that Kaoruko is actually a witch. And what's more, Kaoruko needs Kaname to help control her awakening power!

When it becomes known that Kaoruko has received the power of the Witch Queen, she and Kaname are ordered to appear before the coven of the Black Witches. There, Kaoruko discovers that she must become a Black Witch in order to control her rampaging powers. But that means she will be offered up to an incubus--who presents himself as Kaname as he closes in on her!