My Dear Bodyguard.

Han Bin, an elite private bodyguard, failed in his mission to protect the Sherry's family. As a result of that, her whole family was brutally killed, and the high-tech biotechnology capsule researched by the head of it, was lost. After that, Han Bin decided to quit his job and soon disappeared. However, his old partner convinces him to return to his profession and a peculiar dropped case, since they've recently found a possible suspect of the tragedy - a girl named An Ji.