Lucas is a CEO of a large company who disguises himself as a bodyguard. Your father will match you up with Lucas, but your father orders Lucas to disguise himself as your bodyguard first to protect you and get to know you. and Lucas not allowed to tell you about his real job as CEO even the arranged marriage of you and Lucas.

one day Lucas meet you and speak "From now on, I will be your bodyguard. and you are my responsibility"