Hikaru Shidou, Umi Ryuuzaki, Fuu Hououji are on a field trip to the Tokyo Tower with their respective schools. The girls are blinded by a flash of light and hear a voice calling for the Legendary Magic Knights to save Cephiro. They fall through the sky into another world, Cephiro. Once there, they meet Master Mage Clef. Clef explains, "In Cephiro, one's will has the ability to change reality for better or worse. The dark fears in people's hearts become monsters, while a well-intended wish can do miracles. One person, the Pillar, whose will is stronger than anyone else's, is responsible for maintaining through her prayers the well-being of Cephiro."
In the first story arc, the current Pillar, Princess Emeraude, has been captured by her high priest, Zagato. The three girls are charged with the task of saving the Princess.
Magic Knight Rayearth follows Hikaru, Fuu and Umi along with their friendly sidekick, Mokona, on their quest to save the mystical planet of Cephiro.
