Ophelia-ga Gongjakgareul Beoseonaji Motaneun Iyu

When her mother remarries into the Arpad dukedom, Ophelia finds herself uprooted into the Arpad nobility. However, due to a tragic carriage accident, Ophelia's mother and stepfather suddenly lose their lives. Alexander, her stepbrother, urges her to stay in the Arpad household for the next three years.
One day, Ophelia hears devastating news from an investigator that changes everything.
"The deaths of the Duke and Duchess of Arpad that took place this very day, three years ago... were not accidental deaths, but murders."
(Source: POCKET COMICS)