A leather-clad female physically punishing a compliant male into erotic bliss is the usual image one conjures for BDSM, or bondage, discipline, sadism and masochism. Yet, to spend a Sunday afternoon with the ladies on the roster of La Siora, a high-end club based in Shinjuku, is to realize that the proper delivery of the craft's techniques involves much more than wanton, grip-it-and-rip-it whipping.

A dominatrix, or mistress, must be proficient in handling a wide range of equipment, be able to read the body language of a "slave," and ensure sanitary conditions at all times. But perhaps the greatest challenge involves the law.

Up until last year, La Siora, which opened in 1997, served its clientele out of an apartment building in Yoyogi, Shibuya Ward. Last April, a violation of the Law Regulating Adult Entertainment Businesses occurred during a session in which a dominatrix gave a 29-year-old male customer a sexual service not involving intercourse but still illegal given the in-house business arrangement and the club's registration as deri-heru (or delivery health, meaning an out-call service). The police, who made three arrests, had allegedly been alerted to the incident by nearby residents complaining of noise emanating from behind the closed doors.