My Bodyguard is a Grandmaster?

Liam is passing as an ordinary security guard. He was trained on a mountain as a fighter and came down from it with one job, to guard Jolin, the heiress at the head of the company. On his first day at work he offends her, and she starts looking into him. She keeps at it day after day. The sons of other rich families, who see him as competition for her, make threats against him. Liam is afraid that someone will find out who he is. While he is guarding Jolin he discovers that she is the girl he played with as a child and lost track of years ago. That opens up the question of where he himself came from. He learns who his family was and how every one of them was killed. By then there is nobody who can beat him in a fight, and he sets out after the people who did it.