Lima Syndrome Dramas

Do anyone knows any kdrama/cdrama that has storyline like The main lead is killer/psychopath /mafia. He will kidnapp people and kills everyone. And then one day, he will kidnapp the female lead to kill her but then at one point he will start to fall in love with her.After that, he will change himself for her/ kill people to protect her. 

This type of story is called as Lima Syndrome