My Bodyguard Is 4 Feet Tall

Qin, a man who is about to enter his 30s, runs a private detective office on the surface, but behind the scenes he runs a drug business that can make people mutate. This seemingly "carefree" life was broken by the intrusion of a mysterious boy named Ian who declared that from now on, he would protect Qin, whose parents died. In the face of this "little bodyguard" who insisted on living with him, what will Qin do?