The artificial sun that lights the frozen planet La Metalle is dying, threatening to extinguish what little life is left there. Queen La Andromeda Prometheum decides that the only way for her people to survive is for them to submit to Hardgear's transformation process, which will turn everyone's body into machines. The Queen's daughters, Emeraldas and Maetel, refuse to submit to this process, and fight to stay human.

The series is set in a near-future world where the boundary between human being and AI is vague. A rapid biological evolution, similar to "Cambrian Explosion," is caused by one incident. This incident turns into the genesis of a new jostle for supremacy, and the influence of the evolution goes beyond biological framework and spreads to various kinds of materials and technologies. The era of massive evolution involving diverse existences, such as human, machines, and biotechnologies, is coming. Characters fight an existential war in such a world. (Source: ANN)

On his 16th birthday, Tomokazu Mikuri had a realistic dream where he sees a girl battling a giant floating monstrosity. When he wakes up, he is surprised that the girl is actually sleeping next to him... Whenever he sleeps from now on, he ends up back at the dream world, and more and more people that he knows keep showing up there too. He finds out from a mysterious masked woman in the dream world named Silk that they are fighting against one named Faydoom, and he is the one who provides the powers to those girls so that they can fight these monsters. And so it goes... (Source: ANN)

Okano Makoto transferred to the school in his home town. There, he spent normal but happy school days with his sister, Hinata, a jokey classmate, Tachibana Tsutomu, Shikouin Kasumi, Tsutomu's childhood friend, and other friends. One day, after school, Makoto heard someone playing the harmonica. That melody made him feel something old, and it brought him to the roof of the school buildings. There, he met a girl in the dusk. It was Narukaze Minamo who turned her face to him with a smile. She was a childhood friend, but they had lived separately for years. Hiding their true thoughts, Makoto and his friends spend their lives in school. Their stories in a mysterious town are about to begin.