Haha, now that you mention it.
It was next door to a beautician on the same floor. The mrs used to go there and told me that the owner told her that they complained about their neighbor to the agent. Obviously I was interested but could not go. Eventually the beautician moved to Hornsby so I had a quick look for the massage shop but it too had closed.
There is another upstairs place above BUPA down the road. Nice people, normal service, but not Japanese.