Gate Keepers started out as a Turn-Based Strategy (with Dating Sim elements) video game for the Playstation in 1999.
When it was later adapted into an anime series by GONZO, they decided to omit one of the main Gatekeepers, Francine Allumage and replace her with another with another character.
The story takes place on Earth, after the end of World War II. Alien creatures known simply as Invaders are infiltrating Earth and attempting to take over the world by turning humans into soulless robot-like monsters. The only means to defeat the Invaders is by tapping into powerful energy locked inside dimensional "Gate".
- Francine Allumage appears in the game as one of the lead characters.