Yuuko Asou starts another school day as normal. When school ends, it suddenly starts to rain, so Yuuko tries to find refuge. In doing so, she encounters a fellow student, Reiko Kirishima, who talks with her and leaves her with many unanswered questions. Inmediately afterward, Yuuko is attacked by a monster but a sword appears which she uses to protect herself. She tries to run home only to see that the entire city is being attacked by monsters. After defeating them, queen Valia appears in front of Yuuko telling her that the sword named Valis summoned her to save the dream world, Vecanti, from the claws of the evil emperor Rogles, so she can also save the human world.
Yuko Asou is a schoolgirl in late 1980s Japan who is fated to protect three different realms – our own Earth, the land of spirits, and Vecanti, the Dream World – by wielding a mystical sword known as Valis. Demon lord Rogles extinguishes a light in Vecanti which functions as a source of power for those who live there, and in a desperate plea for salvation, its queen Valia reaches out for a brave soul who can help them in their time of despair. Yuko on Earth is the one who answers the call, being summoned by magical forces into Vecanti to liberate them from the evil of Rogles.