Based on COLOPL's school action role-playing game. Set in the year 2045. The world has been contaminated by Irousu (mysterious invaders who suddenly appeared), and humans find themselves restricted and contained. Standing boldly against these invaders are ordinary girls everywhere, without a powerful army or even weapons. The Shinjugamine Girls Academy is a school for these "Hoshimori" (Star Guardians) destined to fight the Irousu. The player is assigned to this academy to train the girls and take back the contaminated Earth. And so, once again, the chimes echo through the sun-strewn schoolyard to mark the beginning of classes today...

Mitsuo encountered Superman, an alien who is a part of a federation that tries to maintain peace in the galaxy. He then received a helmet (that also serves as a mask) that gives superhuman strength, a cape that enables the wearer to fly, and a badge that allows him to breathe underwater and communicate with his fellow comrades whom he met soon after he utilized these gifts. Superman made it clear to all Permans that their identity must be kept a secret or their brain will be destroyed should it ever be revealed and they are given a special doppelganger robot that can replace them while they are away to achieve this feat, although it is not entirely foolproof nor is it free from potential problems. These equipments then allowed them to be young Permans who try to maintain peace and help the people who are in need.

Friends will only let you down—that is the sad truth Mei Tachibana lives with, ever since she was wrongfully blamed for the death of a class pet by her so-called friends in grade school. Since then, she stays away from people in order to avoid ever being hurt again. However, Mei's life begins to change drastically when a misunderstanding in high school causes her to encounter popular student Yamato Kurosawa. Yamato finds her intriguing and insists on being her friend, even though Mei wants nothing to do with him. But when a dangerous situation ends with Yamato kissing Mei to save her from the unwanted attention of a stalker, Mei begins to develop feelings for him. On the heels of her discovery that their feelings are mutual, they start dating and she gains not only a boyfriend, but friends as well. Mei, however, finds it very hard to adapt to this new lifestyle, especially in expressing her true feelings towards Yamato. Throughout misunderstandings of their new relationship, each other, and the attentions of other girls, Mei and Yamato slowly grow closer and learn the true meaning of those three little words: "I love you."

For as long as Akari can remember, she and Hiroyuki have always been friends. But with time, everything changes, and her feelings have turned into something more. As a new semester of high school begins, will the two childhood friends come closer together or drift further apart? Join Hiroyuki, Akari and all their friends—the bubbly Shiho, the quiet Serika, the lovely Kotone, and more—in this heartwarming tale of love, relationships and friendship!