"Ultimate Girls" is a 12-episode anime series that blends elements of comedy, action, and science fiction. The story centers around three high school girls—Aoi, Rei, and Mai—who are unexpectedly recruited to become Earth's defenders against an alien threat. The trio is chosen by a mysterious organization known as the Ultimate Girls Project, which equips them with advanced battle suits and weapons. These suits grant them enhanced abilities, transforming them into powerful warriors capable of combating extraterrestrial invaders.

The narrative unfolds as the girls balance their ordinary lives as students with their newfound responsibilities as protectors of the planet. Each episode features episodic battles against various alien adversaries, often accompanied by comedic moments and lighthearted interactions among the characters. The aliens, referred to as "Invaders," are depicted as bizarre and often humorous creatures, adding a playful tone to the series despite the high-stakes premise.

Aoi, the protagonist, is portrayed as a cheerful and determined leader, while Rei is the more serious and analytical member of the group. Mai, on the other hand, is characterized by her carefree and somewhat lazy demeanor, providing a contrast to her teammates. Their dynamic is a key element of the series, with their personalities clashing and complementing each other in both battle and everyday situations.

As the story progresses, the girls face increasingly challenging foes, forcing them to grow stronger and work together more effectively. The series also introduces a rival team of Ultimate Girls, adding a layer of competition and tension. While the overarching plot remains relatively simple, the focus is on the characters' development and their ability to adapt to their dual roles as students and warriors.

The anime concludes with a climactic battle against a powerful alien leader, testing the girls' resolve and teamwork. The resolution ties up the main narrative threads while leaving room for potential future adventures. Throughout the series, the tone remains light and entertaining, with an emphasis on humor and camaraderie rather than deep philosophical or emotional exploration.