Sixth-grade student Yuri Otani is elected by her class to be one of the three members of Elementary School 9's "Alien Party," alongside fellow "Alien Fighters" Kumi Kawamura and Kasumi Tomine. They are expected to preferably capture, not kill, any aliens that invade school grounds. Aiding their endeavors are advisor Ms. Megumi Hisakawa and symbiotic aliens named "Borg" that attach to their host's head to protect them from danger.

The main reason why Yuri hates to be in the Alien Party is due to her fear of aliens. If she doesn't outright faint at the sight of them, then her fear keeps her frozen in place so that she can't get the job done. As such, Kumi, Kasumi, and Yuri's Borg have to pick up her slack. Ms. Hisakawa tells the girls that the better they can fuse with their Borgs, the more effective at their job they will be. But could there be another reason behind the existence of the Alien Party and the relationship between girls and Borgs?