Sosuke Sagara is an elite soldier who belongs to an independent special force named \"Mithril\". Mithril is a self appointed military force that fights terrorism across the globe. With technology that is far superior to that of normal nations, Mithril intercedes on behalf of justice. Sagara, a Second Lieutenant under Mithril\'s command, is assigned to the duty of protecting a girl named Kaname Chidori, who attends high school in Japan. To accomplish this task, he pretends to be a transfer student attending at Kaname\'s school. As Sagara settles into his new role as classmate, a massive plot unfolds beginning with the kidnapping of Kaname.