After running a string of reader-participation games between 1993 and 1998, "Dengeki G's Magazine" started "Sister Princess" in March 1999; this would prove to make the magazine very popular, and became a major focus of the magazine for several years. Nearly all the magazine's covers between 1999 and 2003 featured characters from "Sister Princess". After overwhelming support for the project, the series was adapted into a two-series anime, and a string of video games; finally, the serialization of the game ending with the September 2003 issue. At the time, the second TV anime adaptation of another of "Dengeki G's Magazine'"s reader-participation games, "Happy Lesson", was just ending, but the series had proved popular. Seeing how popular their reader-participation games could get, MediaWorks continued to create reader-participation games, something the magazine is well known for today. After "Sister Princess" ended, the editorial department looked to another reader-participation game which started in the October 2002 issue called "Futakoi", and the editors wanted to make this game "Dengeki G's Magazine"s next main focus; the game lasted until October 2005.