In the near future, individuals possessing a special ability known as Sevens exist. The country appears to have maintained peace through the Sumeragi Group, yet they are the ones who forcibly captured these individuals and subjected them to inhumane experiments. Gunvolt, the protagonist who holds the power of a Seven, formerly belonged to Feather, a resistance group fighting against the Sumeragi Group. The narrative commences with his encounter with the heroine, Sian.