The mamasans in Osaka are the worst. If you tell them you are not interested they will literally grab you off the street. I mean I know Osaka is the city of the hard sell, but... geez.
Though the mamasans and bar girls in WanChai in Hong Kong can be quite aggressive. Leave a hand for them to grab and you'll be yanked into the bar very quickly!!
The one in Japan is the only one I know of. I was surprised myself, given how Westernized Japan is compared to the rest of Asia, and how nominally illegal prostitution is there now.
