I, the Invisible Guard, Saved the Female President at the Beginning

I, Lin Chen, codename "Shadow". Once the ace of the top special forces, he accidentally awakened his invisibility during a mission and became a "faceless man" who can perfectly blend into the darkness. After retiring, he just wanted to live an ordinary life, but he was hired by the female CEO at a huge price and became her personal bodyguard. Someone wants to do something to her? I can appear behind you silently, or I can throw you into the river under surveillance without leaving even a trace. No one knows who I am, no one can catch my shadow. In the shadow of this city, I am the rule.