The story is set in Asia in 2020 when West and East cultures are mixed in confusion. A young girl Genpou Shiori is a descendant of the the Phantomhive noble family. Shiori runs a large enterprise, Funtom Company, and she disguises herself in male attire, naming herself “Kiyoharu”. The family only allows males to be the head of the family, and they have also been tasked with the duty to solve difficult cases that happen in the underbelly of society by order of the queen. In order to get revenge, she gave up her life as a woman and made a contract with the demon butler, Sebastian Michaelis, in which Sebastian protects Shiori until she completes her revenge in exchange for devouring her soul.