A large Japanese conglomerate recently banned male and female employees going out together for dinner in pairs. Both must be male or both female. Or they must go in a bigger group. The same applies to business trips.
I know this from an employee who told me the story as we were having a business drink together one evening. Even though he is a man and I am a woman our encounter passed his company's rules because I am not a fellow staff member but an outside consultant.
