As of 2003, at the age 26, Tanaka started developing SNS GREE as a hobby. In February 2004, Tanaka opened SNS GREE to the public, as a personal website. By March 2004, over 10,000 users had joined the SNS that soon became hard for him to manage rapidly growing Service by himself. In December 2004, Tanaka established a company, GREE, Inc. in order to run the Service for the growing number of users.