Tsubasa Shiina is a timid grade schooler who is forced to move to
Hokkaido from
Tokyo with her father, as he pursues his dream of being a baker in the aftermath of her mother's death. At her new school, she is very shy and unsociable with her classmates ignoring her at best, and abusing her inability to defend herself at worst. One night shortly after the Tsubasa and her father begin to settle in their new home, an alien spaceship comes crashing down to earth in the forest behind their house. Stumbling across the ship with her dog, Tsubasa discovers the alien pilot, unconscious and wounded, as well as a monster attempting to kill him. The alien awakes and attempts to fight off the monster, while Tsubasa, in her fright, tries to hide from the monster inside of the ship. The monster quickly overtakes the alien, seemingly killing him and in the process releasing him from some sort of transformation, before attempting to reach Tsubasa within the ship. In its effort, the monster accidentally cracks a mysterious container open, causing the mostly-liquid contents to leak onto the floor next to Tsubasa. After the liquid makes contact with Tsubasa, it converges onto her as a strange substance, which then transforms her into what appears to be the teenage female equivalent of the form that the alien had transformed into while fighting the monster. With the aid of this mysterious power, Tsubasa is able to defeat the monster, although somewhat accidentally. Once the battle is over, Tsubasa reverts to her normal form, though the strange substance turns into an visually identical copy of herself upon separation. The alien awakens, and together, all three return to Tsubasa's house to stay the night in her room. The next day, the alien introduces himself as D.D. and explains that he was transporting the seeds of a monster called a "Maguar", however one of the seeds had hatched and attacked him, forcing his ship to crash land on Earth. The copy of Tsubasa, who claims the name of Hikaru, is revealed as a type of combat suit known as a Figure which has for some reason assumed its current form and retained all of Tsubasa's memories. The Maguar which Tsubasa had defeated was only one of the six Maguars D.D. had been transporting, as the rest are now scattered unknowingly throughout
Hokkaidō. As Earth's atmosphere has enhanced both Hikaru and the Maguars, and one of the original Maguars is later revealed to have laid eggs, it becomes clear that D.D. must have the girls help to carry out the secret eradication of the Maguar infestation. To resolve the issue of Hikaru's sudden presence, D.D., disguising himself as a visiting photographer friend, modifies the memories of Tsubasa's father to make him believe he had twin daughters all along and Hikaru was simply living elsewhere with an aunt, and so Tsubasa and Hikaru begin living together in Tsubasa's house, go to school together at Tsubasa's school, and fight together as Figure 17 against the Maguar, growing the emotional bond between the two in the process. ==Characters==