Centuries ago, mankind abandoned planet Earth after the Vice, a race of mechanical aliens, drove them from their home into a life adrift in space. Now resigned to starships forged of pieces of Earth’s shattered moon, the final hope for humanity lies in the hands of Actresses, young women born with the ability to wield the only weapons that can harm the Vice: Alice Gears, mechanical suits that can finally turn the tide against the alien incursion. (Source: HIDIVE)

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... (Source: ANN, edited)

The world is divided into two kingdoms: the Kingdom of White, which floats in the heavens and is ruled by their queen Iris, and the Kingdom of Black, which stands upon desolate land below and houses the King of Darkness as its ruler. As of late, forces of evil have amassed great power, posing a threat to the entire world. Being the main representative of the Light, it is Iris' duty to maintain the balance of the world and fight off the darkness in her kingdom. Meanwhile in the Kingdom of Black, rampaging monsters annihilate a certain boy's village, leaving him the sole survivor. As he grieves in hopelessness, an armored man named Skeer notices the child and comforts him. Soon after, Skeer recognizes the boy's potential to change the kingdom's status quo and makes him his heir before passing away. The boy then vows to become the Prince of Darkness—the one who will replace the King—to bring the world back to its rightful path. As Iris and Prince of Darkness each challenge the impending doom the world faces in their own respective ways, their destinies will converge with each other, and perhaps, their bond will decide the fate of the world.