Takane Takamine is great at everything she does, and her magnetic personality makes her the envy of everyone. She gets good grades, excels at sports, and even manages to become student council president during her first year of high school. But Takamine has a secret—she possesses an ability called "Eternal Virgin Road," allowing her to redo past actions and achieve a different result. While this might seem like a decent skill to have, Takamine must pay a price to activate it: she has to strip off a piece of her lingerie. After getting an imperfect score on a test, Takamine begins to remove her underwear during class and is spotted by her average and weak-willed classmate Koushi Shirota, who is bewildered by the sight. However, the very next instant, things reset and Takamine's test is now perfect. When Shirota decides to confront Takamine about her previous test score, she reveals her ability to him and blackmails him into becoming her "closet," making him carry around extra lingerie and put them on her. Her goal is to be able to use Eternal Virgin Road as much as possible in order to stay at the top of the school hierarchy. Left with little choice in the matter, Shirota accepts, starting an oddly intimate type of relationship with the most popular girl at school.

In the middle of another break from school, A-Ko dreams of finding the perfect boyfriend. Because of this, she and C-Ko get into an argument that leads to C-Ko running away and nearly getting hit by a motorcyclist named Kei. While working part-time at a fast-food restaurant to raise money for a party dress, A-Ko meets Kei and immediately falls in love with him. B-Ko happens to like him as well; however, both A-Ko and B-Ko are unaware that C-Ko is the apple of Kei's eyes.

In Iraq, a group of archaeologists discover ancient relics that prophecize the coming of a superior race and the end of all civilization. Meanwhile, back in Graviton City, as A-Ko and B-Ko's rivalry over Kei intensifies, Mr. Daitokuji sets up an arranged marriage between Miss Ayumi and Kei. Furious over the engagement, both A-Ko and B-Ko do whatever it takes to prevent the wedding from going through. Little do they know that another alien fleet is on its way towards Earth.

Three weeks after the incident that left Captain Napolipolita's ship balancing on top of Graviton City, A-Ko and the gang go on summer vacation. While A-Ko ponders losing some weight and B-Ko devises another plan to defeat her redheaded rival to win C-Ko, Napolipolita and Spy-D experience severe homesickness - begging for a way to return to their home planet. Meanwhile, Hikari Daitokuji - B-Ko's father and the CEO of the Daitokuji Financial Group - arms the local military with new mecha to attack Napolipolita's ship and obtain its advanced technology.