While I have your ear, I have a question about your comments regarding getting feedback:
You mention that you ask for feedback in your welcome mail as well as on Twitter and FB, which are both in English. Do you find that a large number of your users are open to the idea of using the English versions of your FB & Twitter accounts? If so, do you find that this is a product of being in the Tokyo area?
I used to sell security software and many of our competitors were using solutions developed abroad that in many cases were not translated, or translated poorly. In our experience even when the competition was leagues better than our solution, we won out contracts because of full-Japanese support, and the image of quality that comes from that. This may be a result of being in the Nagoya area, but I was curious about your experiences with "Japanese Only!" customers / clients.
Also, cheers on a great product, and that amazing hockey-stick of growth.