This suggestive little phrase originally meant opening the books, or providing additional information about a company, to an outsider - typically a potential investor, employee, merger partner, acquirer. But it is also used as a metaphor for "organisational openness and transparency".
According to the Microsoft Lexicon it is:
"A marvelous phrase of non-Microsoft origin, probably stemming from the rash of Japanese acquisitions of American enterprises in the ‘80s, that has been adopted into the Microspeak marketing lexicon. Basically a somewhat sexist synonym for "open the books," it means to reveal the inner workings of a project or company to a prospective new partner".Those who like to "open the kimono" praise it for its vividness, but - quite apart from the "somewhat sexist" connotations - it feels almost too vivid for use in business meetings. To me, at least, the image of kimono-swathed businessmen opening their robes and letting it all hang out - or alternatively, trying to get a peek under somebody else's kimono - is too distracting, too comical and too suggestive of striptease for such a serious setting. But after reading reports this week of a financier who attended overseas meeting accompanied by an escort in "revealing hot pants and high heeled shoes", I think I may have been underestimating the tolerance for burlesque in business.