Toru Kokonoe enrolls in Koryo Academy, a high school where its students battle each other with weapons known as Blaze (焔牙/ブレイズ, Bureizu) as training to become future peacekeepers. The students must pass a battle during the qualification ceremony of the freshmen day in order to be enrolled in the academy. Although most students manifest their Blazes as melee weapons, Tor's ability manifests as a shield, making him an Irregular (イレギュラー, iregyurā). The school uses a special Duo system in which students are assigned partners. Tor is paired with Julie Sigtuna, a silver-haired girl from Scandinavia, and must share a room with her.