Apparently they fax party invitations:
As of March, according to Japan’s Cabinet Office, fax machines could be found in 59 percent of Japanese homes. (That penetration rate, after climbing for years, has peaked in the past five years.)
Coming up with a similar number for the United States would require a “polite fiction,” said Jonathan Coopersmith, a Texas A&M University associate professor and an expert on the history of the facsimile. But even in the early 1990s, only about 3 percent of U.S. homes had the machines, he said.