After Tomo Yamanobe's father, the former headmaster of Saint Mikhailov Academy, vanished, all he left behind was a piece of artwork known as the "icon." Not long after his disappearance, rumors spread about a serial killer targeting female students at the academy.
While walking home with her sister Mafuyu Oribe after being bullied at school, Tomo stumbles over an injured silver-haired boy who quickly disappears as she tries to help him. Mafuyu goes to search for him and discovers that the church housing the icon is on fire. When she attempts to rescue the painting, the rumored serial killer suddenly attacks her using a mysterious power to control magnesium. Out of nowhere, the silver-haired boy, who can control iron, appears and saves Mafuyu.
Mafuyu learns that the boy, named Alexander Nikolaevich "Sasha" Hell, is a "qwaser"—a being capable of manipulating an element through the power of "soma," obtained by breastfeeding. Confused by the incident, Mafuyu tries to move on, but has little success when Sasha transfers into her class the next day. What will become of Tomo and Mafuyu's ordinary school life with the threat of other qwasers looming near?