The Tokyo kinbaku (bondage) scene can seem all but invisible to the uninitiated, but, like with all subcultures, if you poke around a bit, you'll be amazed at just how deep this rabbit-hole goes.
A general rule of thumb is this: The more publicized the event is, the more "performance" it is. The low-key, nonadvertised events are likely to be much more raw. Choose accordingly.
A good place for a beginner to start is a place like Shinjuku Loft Plus One , which holds live S&M shows on a regular basis. Loft has been a seedy little venue since the days of 1980s punk, but it does have the advantage of being a live venue. The easily embarrassed do not have to steel themselves to enter an actual sex establishment in order to see some kinbaku.