Over the past year, major U.S. social-media services have made some serious inroads into Japan. Here are some recent developments.

A report on Japanese social-networking services usage issued by Nielsen/NetRatings on Nov. 18 made a huge impact in Japan, as the statistics indicated that the number of Mixi users (8.39 million) has fallen below that of Facebook users (11.31 million).

This news was widely picked up by the Japanese media — forcing Mixi to issue an official statement that it has 15.16 million active users. According to Mixi, the Nielsen research only includes traffic coming from personal computers, which accounts for approximately half of Mixi's users. In the company's financial report issued Nov. 2, it states that 80 percent of the traffic to the site is coming from mobile phones, while there is no sign that the majority of Japanese Facebook users are accessing Facebook from their mobiles.