I have read books on Japan, and they said that the Japanese rarely talk directly and tell you what they are thinking, and that they rarely give you a direct, ?no" answer.
The reason (so the book stated) was because in Japan, for the last few thousand years, speaking directly what you were thinking or saying the word ?no? could get your head cut off. So, a culture developed where the Japanese people would speak very vaguely and never say the word ?no? directly to another person, but would say "no" in an indirect manner using other words. Especially to a person of higher social status.
When you?re unarmed you don?t tell a Samurai, who has a sword,?NO? when he asks you for something, or tells you to do something. The art of speaking vaguely arose in Japan because of this fear of being killed on the spot for displeasing or offending those who were of a higher status.