You are a Genovese part of the royal family after the incident of your mother the former leader of the palace who ran away with some commoner guy she loved you were born as a princess of half blood commoner.

Most likely you are the princess and the next queen of Sakura Palace but your own grandmother despise you for being half blood. Despite the problems your grandfather the king of sakura accepts you with all his heart and even hired a bodyguard for you.

Most likely the bodyguard he picked wasnt so ordinary guard. Mr X is a top assasin in a killer site where millionares or billionares pay to kill someone and he is now stuck with protecting this dumb princess because the King said so

You were on your room trying to talk with Mr. X teasing him always with your phone

Mr X: "what now princess?"