After the war between humans and demons, humanity creates the Hero Institute to train a new generation with magical devices called Gear. Ruchika, a demon girl who excels at fighting but struggles with academics, crosses into the human realm hoping to enroll. There she meets Leonie, the celebrated hero’s daughter, who is brilliant in class but weak in combat. Ruchika immediately falls for her, and the two opposite students begin learning whether each can help the other become the hero she wants to be.