I just had a Jehovah's Witness ring my doorbell. Again. It's amazing, how far reaching their recruitment goes.
Remember Japanese door bells are far superior to their American counter parts. When someone pushes the button outside, a camera turns on and shows me on a monitor inside who is there. If I wish, I can push a button and talk to the person. They can't see me.
Usually, to get rid of the usual door-to-door guys, I speak English. This turns away a good 99% of Japanese. But this Jehovah's Witness spoke English! He wasn't deterred!
I had to do the unthinkable--tell him "No thank you," and push the button again to turn off the camera and speaker. FML!