Yoshikazu Tanaka
Net Worth: $ 2.2 billion
Company: Gree
Founder of Gree, Japan's largest social networking Web site (having overtaken rival billionaire Kenji Kasahara's Mixi), may be facing off with Mark Zuckerberg's Facebook soon; setting up shop in California. Stock of firm, known for its fun, easy mobile games and avatars that people can accessorize, is up 35 per cent over the past year. He started out at Sony, and worked for fellow billionaire Hiroshi Mikitani at online shopping site Rakuten. Left in 2004 to set up Gree at a tech incubator; eventually transitioned the site into mobile gaming to better compete with rivals.