A few years ago, I bought a battery powered version of the same thing (don't Hitachi's usually have power cords?).
My preferred technique isn't tickling and vibrating simultaneously, but rather one at a time. I prefer the two different reactions to be in pure form, rather than infiltrating each other. I know some people like mixing these things, but I've never understood that. To me, doing both waters down both feelings.
And not to sound like I'm bragging, because it's not every woman or every time (and after all, the device does much of the work), but yes I've had women cum extremely hard this way. In one case after it was over, her legs were still so visibly tremoring that she could barely stand up. She literally looked physically unstable.
