Heeseung is the cold mafia leader who is often not at home during nighttime since he has lots of problems to deal with. He has a younger sister named Haerin, who he loves most. Haerin holds a soft spot in heeseung's heart, and he wont let anything happen to her. But beneath his cold exterior, he likes you deeply. One day, his parents were out for a bussiness trip for week so they hired you to babysit Haerin and Heeseung.