What Is mixi? Japan's Invitation-Only Social Network and Its Turn to Monster Strike

mixi is a Japanese social network that began in 2004. If the question is when it started, the answer is February 2004: MIXI's corporate history says the company began operating the social network that month, and according to Nlab (ITmedia) it pre-opened on 22 February and fully launched on 3 March. It was known for being invitation-only, so that you could not join unless an existing member invited you, and its users passed 20 million in April 2010. Use then fell during the shift to smartphones, and the company rebuilt itself on the smartphone game Monster Strike.

An invitation-only network

mixi's operator started out as a recruitment company. According to MIXI's corporate history, it launched the job site Find Job! in November 1997 and set up e-Mercury, a limited company, in June 1999 to run it. mixi was a new business it began in February 2004; the company renamed itself mixi in February 2006 and listed on the Tokyo Stock Exchange's Mothers market that September.

What set mixi apart was that you needed an invitation from a member to get in. An ITmedia article in November 2008 wrote that the invitation system had been part of mixi's identity. According to Nlab, mixi stayed in beta for a long time after launch.

Membership grew quickly. According to INTERNET Watch, mixi announced on 21 May 2007 that its users had passed 10 million the previous day, 20 May, three years and three months after launch.

These are counts of registered users, not of people using the service each month. The same INTERNET Watch article reported that, as of 31 March 2007, women made up 52.1% of PC users and 56.6% of mobile users, and that the Tokyo metropolitan area accounted for more than 40% of users on both.

Opening up, and Twitter and Facebook

On 27 November 2008 mixi announced the end of invitation-only sign-up. According to ITmedia, it planned to introduce registration without an invitation in spring 2009, and, as a first step from 10 December, to lower the minimum age from 18 so that 15- to 17-year-olds could join. Open registration actually arrived later than planned, on 1 March 2010. According to INTERNET Watch, sign-up by invitation continued alongside it, and new users had to verify themselves by mobile phone to stop one person creating multiple accounts.

The following month, April 2010, users passed 20 million. According to ITmedia, the president, Kenji Kasahara, responding to reports that some users logged in less after starting Twitter, said that public posting on Twitter and "mixi Voice", limited to friends, would likely coexist over the medium to long term. He named Facebook and Chinese social networks as the real competition, saying that even Facebook, the world's largest, had only 400 million users and the race had just begun.

Decline and a first loss

A few years later the picture had changed. According to INTERNET Watch, mixi's revenue for April–June 2013 fell 39.4% year on year to ¥2.144 billion, with an operating loss of ¥84 million, its first quarterly loss since listing in September 2006. The president, Yusuke Asakura, blamed lower advertising revenue caused by changing devices. According to the same article, users logging in at least once a month through the group's apps and the smartphone version, mixi Touch, fell from 9.93 million in March 2013 to 7.95 million in June.

The turn to Monster Strike

The recovery came from a game, not the social network. According to MIXI's corporate history, the company officially launched the smartphone game Monster Strike in October 2013. According to Toyo Keizai Online, revenue for April–June 2014 was about ¥12.7 billion, around 5.9 times the year before, with operating profit of ¥4.6 billion (against a loss of ¥84 million a year earlier); Monster Strike accounted for about ¥10 billion of the revenue. According to Dengeki Online, Monster Strike's cumulative users worldwide passed 65 million on 12 December 2025 (a figure that excludes repeat downloads on the same device).

The company went on to spread into other businesses. Its corporate history lists the family photo-sharing app Family Album (Mitene) in April 2015, the acquisition of the operator of netkeiba in November 2019, and the change of name to MIXI in October 2022.

mixi2

Twenty years on, the name was used again. On 23 December 2024 MIXI announced that it had launched a new social network, mixi2, on 16 December. The announcement presents mixi2 as a place to share the moment and gather quickly; it is invitation-only and closed to under-18s. Registered users had passed 1.2 million at the time of the announcement, which describes the service as marking twenty years since mixi began in 2004. The original mixi carries on as well: according to Nlab, a 20th-anniversary feature, the mixi Timeline, was added on 4 March 2024.

Lineage

mixi launched in the same month as Facebook, February 2004, and went on to gather more than 20 million registered users in Japan. Where 2channel assumed anonymity, mixi was built on ties between friends and acquaintances. Japanese messaging later moved to LINE, designed for smartphones. For the wider story, see the social media timeline.