Catherine's Key to a Happy Life

Abuse of Power Appearance Different from Actual Age Arrogant Character/s Blue-Eyed Female Lead Broken Engagement Broken Promise/s Brown-Haired Female Lead Brown-Haired Protagonist Calm Female Lead Calm Protagonist Color-Changing Eyes Contract/s Contractual Relationship Deal with the Devil Demon Lover/s Demon Male Lead Demon/s Devil/s Duke Male Lead Duke/s European Ambience Ex-Lover/s Family Feud Fantasy World Fearless Female Lead Female Protagonist Full Color Half-Human Hard-Working Female Lead Haunted House Mage Male Lead Magic Missing Person Mysterious Character/s Mysterious Death Mysterious Elements Mysterious Location Mysterious Male Lead Nobility/Aristocracy Poor to Rich Purple/Violet-Eyed Male Lead Rich Male Lead Searching for Family Member/s Secret Identity Stepmother/s Stepsister/s Strong Male Lead Strong-Willed Female Lead Unique Ability/ies White/Silver-Haired Male Lead