The Japanese word for "yes" is "hai". The Japanese world for "I'm sorry, I haven't a clue what you're talking about, could you repeat it" is also "hai". This can lead to some obvious problems though not as much as the reinterpretation of the actual meaning of "yes" itself.
Recent arrivals to Japan are often surprised to find that business life is significantly simpler than they'd been led to believe as everyone they meet agrees with what they are saying. When asked a question, their Japanese colleagues will often reply "hai". In this instance though, the actual meaning of their response is more akin to "I recognise you're in the room and talking to me, I think I'd like a coffee".
It took me quite a while to understand that I really didn't understand.