The screw that holds the left lense of my glasses had come undone. I stumbled into a narrow stock room and came across a Japanese business man who was working there. I asked him if he had a watchmaker's screwdriver set and after much fumbling round he produced one. He noticed that my "screw" was unbranded and asked as means of paying him back for re-threading it if he could brand it. I asked why and he replied that he wanted to research this screw further. Naturally I obliged him.