Despite only being in closed beta testing at the moment, Google's new social-network service, Google+, is rapidly proving to be huge, with more than 10 million users joining since it was announced on June 28. And thanks to their international connections, Net-savvy Japanese too were soon getting invitations to join "circles," which is how the service organizes members.

Within a day or two of invitations being sent out, I observed a lot of Japanese users joining — with a speed much faster than when social-networking services like Orkut, Mixi, Gree, Twitter and Facebook launched. Many Japanese social-media experts tried out the features of Google+ and numerous blog posts have popped-up explaining how to use the service, which has created quite a buzz among tech readers.

When Paul Allen of the online family resource Ancestry.com estimated on July 12 that the number of Google+ users worldwide would pass 10 million on the 13th, his prediction was based on a search of surnames of registered Google+ users (using U.S. census data to determine what names to search for). I did a similar estimation for Japan, though with a smaller amount of Japanese surname data, and calculated that as of July 14 there were between 500,000 and 1 million Japanese Google+ users.