The first known post-80's-boom panties-flashing cafe was actually a bar in Osaka's (in)famous Minami district that opened its doors in 2006. All female staff members work behind the counter, but wear very short mini-skirts.

While serving customers, the female staff—known as 'Chiradols' which combines 'panchira' (flashing panties) and 'idols'--frequently flashed their panties.

Under the guise of a regular girls bar, they operated from the afternoon into the late evening. Several years ago, there was a boom of maid cafes and most closed their doors one by one as popularity waned. Without skipping a beat nor engaging in much redecoration, many of the failed maid cafes transformed into panty-flashing bars.

In order to avoid the ire of the strict eyes of the law authorities, these panty-flashing cafes never made homepages and simply relied on attracting customers via signage and word-of-mouth. In due time, the trend picked up in Tokyo...

(Translator's note: These types of clubs truly verge into that nefarious gray area though knowing the history the area, a few clubs may have gotten slaps on the wrists and perhaps one or two would shutter their doors, but most would stay open for a time. As popularity wanes, something else will naturally take its place and the cycle will repeat.)