Tsubasa Shiina is a 10-year-old girl who recently moved to Hokkaido to live with her father. In school, she is very quiet and unsociable with her classmates. Then one night, she witnesses a UFO crash in the forest near her home. She rushes to the scene and finds the pilot, codenamed "D.D.", in a barely stable condition. Also in the scene is a Maguar, a hideous alien that hatched aboard D.D.'s ship. As the Maguar is close to taking Tsubasa's life, an alien lifeform fuses with her body to form the Riberus battle armor Figure 17, which shortly destroys the alien threat. The life form takes the name Hikaru and turns into an identical twin of Tsubasa. As time passes, Tsubasa becomes more open to everyone around her, thanks to her new twin sister Hikaru. However, with Maguar eggs scattered all over Hokkaido, their ability to form Figure 17 is needed to eliminate all hatched Maguars until backup from D.D.'s home planet arrives on Earth.

Years ago, the opening of an interdimensional portal released two beasts into the skies over the Sea of Japan, visible to all the countries along the coast. After destroying the naval patrol sent to investigate the disturbance, the two beasts then turned against each other. Witnessing the fight from Japan, scientists Joe and Marie Hayakawa were sucked into the rift. Upon returning to Earth, they compiled and published the academic findings from their voyage in a legendary book titled ''Day of Succession''. Attempting a second expedition to that other dimension twelve years later, the couple have not returned. Twins Ai and Yu Hayakawa decide to set forth in search of their parents and the mysterious Wonderland they studied. In the ruins of an abandoned subway station, the two wait for a train to take them to the world beyond. On board they meet Lisa Pacifist, who quickly decides to aid the two in the search for their missing family. Can the three of them manage to find Joe and Marie?

An edited compendium of the four OVAs were spliced together to create a movie which aired in theaters. Included within the was also a prologue, which used 50 extra shots that introduced the world of Dallos before the opening credits.

It is the 25th century. The dark lord has 'infected' history with time-devices that could damage history beyond repair. Flint and his father lived in the prehistorics when they got turned into fossiles. They are discovered and Flint ges turned back to his original state. With the help of his father, a boy Tony and a girl Sara he has to travel trough time to bring the time-devices back to the land of time so history will be saved.