Sex is universal, but kinks can be local. Japanese S&M, at least the varieties I've seen in films over the years, is less about black leather and fishnet stockings, more about candle wax and artfully elaborate knots designed to display the flesh of the (inevitably female) subject in enticing ways.
In the 2007 Ryuichi Hiroki documentary "Bakushi (Bakushi: The Incredible Lives of Rope-Masters)," the ones tying the knots are not sailors but bakushi: deft-fingered masters at the art of bondage, whose finished products are akin to human rope sculpture. Actual sex is not part of the process, at least while Hiroki's cameras are running, and would in any case spoil the effect. Similarly, Japanese haute cuisine is meant to be enjoyed first and foremost by the eyes, with its consumption feeling like an act of desecration, however delicious.
But as Naoto Takenaka's film "R-18 Bungakusho Vol. 1: Jijojibaku no Watashi (R-18 Women's Fiction Prize vol.1: Self Bondage)" vividly demonstrates, some bondage subjects prefer the DIY approach. That is, they tie themselves up as a form of self-eroticism.