Katherine Lilliana Phantomhive is Ciel Phantomhive's younger sister. She's younger than Ciel by one year, which means she's 12. Katherine is a quirky and cheerful girl. She doesn't know Sebastian is a demon and Ciel wants it to stay that way. Sebastian was ordered to serve for Katherine too.
Katherine's one true wish is to make Ciel happy again........And she will do anything to make that happen.