Fifteen-year-old Charlotte Aphrodite Plotekote is the eldest daughter of the Duke.
Her Japanese biological mother, Chiho Riki-kun, died young, so she was not taken seriously by the Duke.
Until Charlotte made an engagement with the second son of the Phantomhive family, who was two years younger than her---
"Mr. Omnipotent white-haired man, benevolent coffin shop owner, I am willing to dedicate my body to you as an experimental product for your flesh puppet."
"I only ask you to protect my former little fiancé from the hands of the devil and ensure that he lives a long life and his soul is intact."
Concept: Half-mother relationship and youthful love in girlhood