Nine-year-old Lae has been living on the streets since her mother passed away, surviving on what little food strangers give her. When she begs a seemingly rich man for coins, she suddenly remembers her past life as Yuna—a sickly child bedridden in a hospital—and the identity of the man before her: Kallen de Lewelton, protagonist of the mystery novel The Life of Duke Lewelton.

Although he is the main character, Kallen is far from an ideal hero. He is known as a bloodthirsty psychopath who finds joy in torturing other killers. Out of self-interest and fear, Lae chooses to help Kallen catch a criminal on the run. Unbeknownst to the little girl, Kallen suspects her timely knowledge, so he invites her to his mansion under the guise of gratitude.

Lae hopes that Kallen will employ her as a maid, giving her the chance to finally escape poverty. Kallen's real offer is one that will change her life forever, albeit in a different way than she imagined—to become his adopted daughter.